9
practice testMultiple Choice

Practice Test

Question 9 • Algebra I

Sergey is solving 5 x squared plus 20 x minus 7 is equal to 0 Which steps could he use to solve the quadratic equation by completing the square? Choose three correct answers.

Answer
A
5 times open paren x squared plus 4 x close paren is equal to negative 7
B
5 times open paren x squared plus 4 x plus 4 close paren is equal to negative 7 plus 20
C
x plus 2 is equal to plus or minus square root of 27 fifths
D
5 times open paren x squared plus 4 x close paren is equal to 7
E
5 times open paren x squared plus 4 x plus 4 close paren is equal to 7 plus 20

Explanation

Move −7 to the right side to get 5(x² + 4x) = 7, which is choice E. To complete the square, add 4 inside the parentheses; because the expression is multiplied by 5, this adds 20 to the right side, giving 5(x² + 4x + 4) = 7 + 20, or choice B. Then divide by 5 and take square roots: (x + 2)² = 27/5, so x + 2 = ±√(27/5), as in choice A.

AI-written and checked against the verified answer.

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