Question

y^4-27y=0 решите уравнение, x^3+7x^2=18x и это

Answer 1

$y^4-27y=0\y(y^3-27)=0\y(y-3)(y^2+3y+9)=0\\y_1=0;\\y-3=0\y_2=3;\\y^2+3y+9=\D:9-36=-27 textless 0;\\y=0; ; 3.\\\x^3+7x^2=18x\x(x^2+7x-18)=0\\x_1=0;\\x^2+7x-18=0\D:49+72=121\x_1,_2=frac{-7pm11}{2}, \x_1=2; qquad x_2=-9.\\x=0; ; 2;; -9.$