Determine the value or values of d that complete the square for the expression.

Question

(a) x^2 + dx +64

(b) x^2 + dx +49/4

Answer 1

that last number = (d/2)^2
so
64 = d^2/4
d^2 = 4 * 64
d = 2*8
d = 16 like (x+8)(x+8)

then the second one
d^2/4 = 49/4
so d = 7
like (x+7/2)(x+7/2) = x^2 + 7 x + 49/4

Answer 2

Lee