Answer:
x = -1 or
x = -7
Step-by-step explanation:
Given DAB and BCD are similar :
2x^2 + 7 = x^2 - 8x make the left side of equation 0 by exporting all terms to right side
2x^2 - x^2 + 8x + 7 = 0 add like terms
x^2 + 8x + 7 = 0
(x + 1) * (x + 7) = 0 in this case x is either -1 or -7
