Solve by completing the square.
-$$x ^ { 2 } + 4 x = 7$$
A) $2 + \sqrt { 11 }$
B) $- 1 \pm \sqrt { 11 }$
C) $- 2 \pm \sqrt { 11 }$
D) $- 2 \pm 2 \sqrt { 11 }$

Question

Quizplus · Accepted Answer

To solve the equation $x^2 + 4x = 7$ by completing the square, first move the constant term to the other side to get $x^2 + 4x - 7 = 0$. Then, add and subtract $(\frac{4}{2})^2 = 4$ inside the equation to complete the square: $x^2 + 4x + 4 - 4 - 7 = 0$, which simplifies to $(x + 2)^2 = 11$. Taking the square root of both sides gives $x + 2 = \pm \sqrt{11}$, so $x = -2 \pm \sqrt{11}$.

Solve by Completing the Square x2+4x=7x ^ { 2 } + 4 x = 7x2+4x=7

Solve by Completing the Square $x ^ { 2 } + 4 x = 7$