Question

calcule (x-5).(x-5)-9=0

Answer 1

$(x-5)(x-5)-9 = 0\\ x^2 -10x +25-9 =0\\ x^2 - 10x+16 = 0\\ Delta = 100 -64 = 36\\ x' = \frac{ -(-10)+ \sqrt{36} }{2*1} = 8\\ x'' = \frac{ -(-10)- \sqrt{36} }{2*1} = 2$