Question

Решите уравнение: (3x+1)²=40+9( x-1)(x+2)

Answer 1

$(3x+1)^2=40+9( x-1)(x+2) \ (3x)^2+2*3x*1+1^2=40+9(x^2-x+2x-2) \ 3^2x^2+6x+1=40+9(x^2+x-2) \ 9x^2+6x+1=40+9x^2+9x-18 \ 9x^2-9x^2+6x-9x=40-18-1 \ -3x=21 \ x=21:(-3) \ x=-7$