Which of the following represents the solution to the equation shown below?

x² + 18x + 81 = 144

A. 3 or -21
Correct! One way to solve this equation is using square roots.

B. -3 or 21
Incorrect. Check the signs.

C. 63 or -81
Incorrect. The square root of 144 is 12, not 72.

D. -63 or 81
Incorrect. The square root of 144 is 12, not 72; incorrect signs.

A student is using the quadratic formula to solve a quadratic equation. The student’s work is shown below.

Which of the following equations is the student solving?

1. 2x² + 5x + 4 = 0
2. -2x² + 5x - 4 = 0
3. -2x² - 5x + 4 = 0
4. -2x² + 5x + 4 = 0

A
Incorrect. Check the a value.

B
Incorrect. Check the c value.

C
Incorrect. Check the b value.

D
Correct! a = -2, b = 5, c = 4

A student is asked to solve the quadratic equation shown below.

9x = 4 − 2x²

Which of the following formulas can be used to solve the equation?

1. 9 ± √113 4
2. -9 ± √113 4
3. -4 ± √88 -4
4. -9 ± √50 4

A
Incorrect. Check the b value.

B
Correct! a = 2, b = 9, c = -4

C
Incorrect. Put the equation in standard form first.

D
Incorrect. 9^2 = 81

Which of the following represents the approximate solution to the quadratic equation shown below?

7x² − x − 12 = 0

A. 1.24, -1.38
Incorrect. Check the signs.

B. -1.31, 1.31
Incorrect. The b value is -1, not 0.

C. -1.24, 1.38
Correct! Solve the equation using the quadratic formula.

D. -0.81, 0.72
Incorrect. The a value is 7, not -12.

Which of the following represents the approximate solution to the quadratic equation shown below?

3x² - 6x = 12

A. -0.83, 4.83
Incorrect. Divide b by 2, and then square the result.

B. 3.24, -1.24
Correct! Put the equation in standard form and use the quadratic formula to solve the equation.

C. -4.83, 0.83
Incorrect. Divide b by 2, square the result and check the signs.

D. -3.24, 1.24
Incorrect. Check the signs.