Back to Intermediate Algebra 2e

2.3 Solve a Formula for a Specific Variable

Rearranging literal equations so any letter becomes the subject, and applying that skill to geometry formulas for area, perimeter, and volume.

Intermediate Algebra 2e, 2.3 Solve a Formula for a Specific Variable

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51 exercises

2.3 Exercise 1

Before you get started, take this readiness quiz.

Evaluate 2(x+3)2 \left(x + 3\right) when x=5.x = 5 .
If you missed this problem, review the reference.

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2.3 Exercise 2

The length of a rectangle is three less than the width. Let w represent the width. Write an expression for the length of the rectangle.
If you missed this problem, review the reference.

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2.3 Exercise 3

Evaluate 12bh\frac{1}{2} b h when b=14b = 14 and h=9.h = 9 .
If you missed this problem, review the reference.

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2.3 Exercise 5

Use the formula A=12bhA = \frac{1}{2} b h to solve for b.

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2.3 Exercise 6

Use the formula A=12bhA = \frac{1}{2} b h to solve for h.

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2.3 Exercise 8

Solve the formula F=95C+32F = \frac{9}{5} C + 32 for C.

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2.3 Exercise 9

Solve the formula A=12h(b+B)A = \frac{1}{2} h \left(b + B\right) for b.

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2.3 Exercise 11

Solve the formula A=P+PrtA = P + P r t for t.

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2.3 Exercise 12

Solve the formula A=P+PrtA = P + P r t for r.

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2.3 Exercise 14

Solve the formula 4x+7y=94 x + 7 y = 9 for y.

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2.3 Exercise 15

Solve the formula 5x+8y=15 x + 8 y = 1 for y.

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2.3 Exercise 17

The area of a triangular church window is 90 square meters. The base of the window is 15 meters. What is the window’s height?

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2.3 Exercise 18

A triangular tent door has an area of 15 square feet. The height is five feet. What is the length of the base?

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2.3 Exercise 20

The measure of one angle of a right triangle is 50 more than the measure of the smallest angle. Find the measures of all three angles.

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2.3 Exercise 21

The measure of one angle of a right triangle is 30 more than the measure of the smallest angle. Find the measures of all three angles.

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2.3 Exercise 26

The length of a rectangle is seven more than twice the width. The perimeter is 110 inches. Find the length and width.

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2.3 Exercise 27

The width of a rectangle is eight yards less than twice the length. The perimeter is 86 yards. Find the length and width.

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2.3 Exercise 29

One side of a triangle is seven inches more than the first side. The third side is four inches less than three times the first. The perimeter is 28 inches. Find the length of the three sides of the triangle.

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2.3 Exercise 30

One side of a triangle is three feet less than the first side. The third side is five feet less than twice the first. The perimeter is 20 feet. Find the length of the three sides of the triangle.

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2.3 Exercise 32

The perimeter of a rectangular swimming pool is 200 feet. The length is 40 feet more than the width. Find the length and width.

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2.3 Exercise 33

The length of a rectangular garden is 30 yards more than the width. The perimeter is 300 yards. Find the length and width.

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2.3 Exercise 37

Solve the given formula for the specified variable.

Solve the formula C=πdC = \pi d for d.

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2.3 Exercise 39

Solve the given formula for the specified variable.

Solve the formula V=LWHV = L W H for L.

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2.3 Exercise 41

Solve the given formula for the specified variable.

Solve the formula A=12bhA = \frac{1}{2} b h for b.

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2.3 Exercise 43

Solve the given formula for the specified variable.

Solve the formula
A=12d1d2A = \frac{1}{2} d_{1} d_{2} for d1.d_{1} .

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2.3 Exercise 45

Solve the given formula for the specified variable.

Solve the formula
A=12h(b1+b2)A = \frac{1}{2} h \left(b_{1} + b_{2}\right) for b1.b_{1} .

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2.3 Exercise 47

Solve the given formula for the specified variable.

Solve the formula
h=54t+12at2h = 54 t + \frac{1}{2} a t^{2} for a.

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2.3 Exercise 49

Solve the given formula for the specified variable.

Solve 180=a+b+c180 = a + b + c for a.

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2.3 Exercise 51

Solve the given formula for the specified variable.

Solve the formula
A=12pl+BA = \frac{1}{2} p l + B for p.

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2.3 Exercise 53

Solve the given formula for the specified variable.

Solve the formula
P=2L+2WP = 2 L + 2 W for L.

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2.3 Exercise 55

Solve for the formula for y.

Solve the formula
8x+y=158 x + y = 15 for y.

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2.3 Exercise 57

Solve for the formula for y.

Solve the formula
−4x+y=−6−4 x + y = −6 for y.

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2.3 Exercise 59

Solve for the formula for y.

Solve the formula
x−y=−4x - y = −4 for y.

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2.3 Exercise 61

Solve for the formula for y.

Solve the formula
4x+3y=74 x + 3 y = 7 for y.

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2.3 Exercise 63

Solve for the formula for y.

Solve the formula
2x+3y=122 x + 3 y = 12 for y.

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2.3 Exercise 65

Solve for the formula for y.

Solve the formula
3x−2y=183 x - 2 y = 18 for y.

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2.3 Exercise 67

Solve using a geometry formula.

A triangular flag has area 0.75 square feet and height 1.5 foot. What is its base?

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2.3 Exercise 69

Solve using a geometry formula.

What is the base of a triangle with area 207 square inches and height 18 inches?

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2.3 Exercise 71

Solve using a geometry formula.

The two smaller angles of a right triangle have equal measures. Find the measures of all three angles.

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2.3 Exercise 73

Solve using a geometry formula.

The angles in a triangle are such that one angle is twice the smallest angle, while the third angle is three times as large as the smallest angle. Find the measures of all three angles.

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2.3 Exercise 87

Solve using a geometry formula.

The width of a rectangle is seven meters less than the length. The perimeter is 58 meters. Find the length and width.

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2.3 Exercise 89

Solve using a geometry formula.

The width of the rectangle is 0.7 meters less than the length. The perimeter of a rectangle is 52.6 meters. Find the dimensions of the rectangle.

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2.3 Exercise 91

Solve using a geometry formula.

The perimeter of a rectangle of 150 feet. The length of the rectangle is twice the width. Find the length and width of the rectangle.

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2.3 Exercise 93

Solve using a geometry formula.

The length of the rectangle is three meters less than twice the width. The perimeter of a rectangle is 36 meters. Find the dimensions of the rectangle.

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2.3 Exercise 95

Solve using a geometry formula.

The perimeter of a triangle is 39 feet. One side of the triangle is one foot longer than the second side. The third side is two feet longer than the second side. Find the length of each side.

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2.3 Exercise 97

Solve using a geometry formula.

One side of a triangle is twice the smallest side. The third side is five feet more than the shortest side. The perimeter is 17 feet. Find the lengths of all three sides.

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2.3 Exercise 99

Solve using a geometry formula.

The perimeter of a rectangular field is 560 yards. The length is 40 yards more than the width. Find the length and width of the field.

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2.3 Exercise 101

Solve using a geometry formula.

A rectangular parking lot has perimeter 250 feet. The length is five feet more than twice the width. Find the length and width of the parking lot.

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2.3 Exercise 107

Converting temperature While on a tour in Greece, Tatyana saw that the temperature was 40° Celsius. Solve for F in the formula C=59(F−32)C = \frac{5}{9} \left(F - 32\right) to find the Fahrenheit temperature.

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2.3 Exercise 109

Christa wants to put a fence around her triangular flowerbed. The sides of the flowerbed are six feet, eight feet and 10 feet. How many feet of fencing will she need to enclose her flowerbed?

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2.3 Exercise 111

If you need to put tile on your kitchen floor, do you need to know the perimeter or the area of the kitchen? Explain your reasoning.

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Adapted from Intermediate Algebra 2e © 2020 Rice University. Licensed under CC BY 4.0. Source: Intermediate Algebra 2e. Imported at revision 77a933c.