Question

Решите уравнение
2x+корень из(4x+21)=7

Answer 1

$2x + sqrt{4x+21} =7; sqrt{4x+21} = 7-2x; sqrt{4x+21 } = ( 7-2x)^{2} ; 4x+21 = 49-28x +4 x^{2} ; 4 x^{2} - 28x+49 - 4x -21 =0; 4 x^{2} -32x +28 = 0;/4 x^{2} - 8x +7 =0; x_{1} =1; x_{2} =7; отв: x = 1;$