Using the Completing the Square method, what are the zeros of the quadratic function f of x is equal to 2 x squared plus 8 x minus 3 ?
Answer
A
x is equal to negative 2 minus square root of 11 halves and x is equal to negative 2 plus square root of 11 halves
B
x is equal to 2 minus square root of 7 halves and x is equal to 2 plus square root of 7 halves
C
x is equal to negative 2 minus square root of 7 halves and x is equal to negative 2 plus square root of 7 halves
D
x is equal to 2 minus square root of 11 halves and x is equal to 2 plus square root of 11 halves
Explanation
Set the function equal to zero and divide by 2: x² + 4x − 3/2 = 0. Completing the square gives (x + 2)² = 11/2, so x = −2 ± √(11/2). Thus the zeros are −2 − √(11/2) and −2 + √(11/2), which is choice B.
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