Question

HELP ASAP! Complete the square. Formula (b/2)²

a²+ 14a − 51 = 0

A. {-3,17}
B. {3,-17}
C. {-3,-17}
D. {3,17}

Answer 1

B

Explanation:

a² + 14a - 51 = 0 ( add 51 to both sides )

a² + 14a = 51

to complete the square

add ( half the coefficient of the x- term )² to both sides

a² + 2(7)a + 49 = 51 + 49

(a + 7)² = 100 ( take square root of both sides )

a + 7 = ±
`√(100)` = ± 10 ( subtract 7 from both sides )

a = - 7 ± 10

then

a = - 7 + 10 = 3

a = - 7 - 10 = - 17