Respuesta :

2x²+16x-10=0

is equivalent to:     (divide by two)

x²+8x-5=0

The answer is d.
(x+4)²= 21

Because,

(x+4)²= 21

x² + 8x +16 = 21

x² + 8x +16  -21= 0

x² + 8x - 5= 0