Question

Solve the equation by completing the square. Round to the nearest hundredth if necessary. x2 + 2x = 15

Answer 1

Hello,

Answer A.

$x^2+2x=15\\ \Rightarrow\ x^2+2x-15=0\\ \Rightarrow\ x^2+2x+1-16=0\\ \Rightarrow\ (x+1)^2-4^2=0\\ \Rightarrow\ (x+1-4)(x+1+4)=0\\ \Rightarrow\ (x-3)(x+5)=0\\ \boxed{\Rightarrow\ x=3\ or\ x=-5}$