Solve the Equation $2 \log _ { 2 } x = 1 + \log _ { 2 } ( x + 40 )$

Multiple Choice

Solve the equation. $2 \log _ { 2 } x = 1 + \log _ { 2 } ( x + 40 )$

A) none of these
B) $x = - 8$
C) $x = 15$
D) $x = 7$
E) $x = 10$