Question

Solve x 2 - 4x - 7 = 0 by completing the square. What are the solutions?

A){2 +√11 , 2 - √11}

B){-2 +√11 , -2 - √11}

C){2 + √11, 2 +√11 }

Answer 1

A) {2 +√11 , 2 - √11}

Explanation:

`x^2 - 4x-7=0\\\\\underline{x^2 - 2\cdot x\cdot2+2^2}-2^2-7 =0\\\\\big(x-2\big)^2-4-7=0\\\\ \big(x-2\big)^2=11\\\\ x-2=\pm√(11)\\\\ x=2\pm√(11)`