Question

решите уравнение x²-5=4x

Answer 1

$x^{2} -5=4x \\ x^{2} -5-4x=0 \\ x^{2} -4x-5=0 \\ D=16+4*5=16+20=36 \\ \sqrt{D} =6 \\ x_{1} = \frac{4+6}{2} = \frac{10}{2} =5 \\ x_{2} = \frac{4-6}{2} =- \frac{2}{2} =-1$