Question

Tìm x

(x²-5)(3+x)+(4+x)(1-x)=30

Giúp với đang cần gấp

Answer 1

\(\left(x^2-5\right)\left(3+x\right)+\left(4+x\right)\left(1-x\right)=30\)

\(x^2\left(3+x\right)-5\left(3+x\right)+4\left(1-x\right)+x\left(1-x\right)=30\)

\(3x^2+x^3-15+5x+4-4x+x-x^2=30\)

\(\left(3x^2+x^3+5x-4x+x-x^2\right)-\left(15-4\right)=30\)

\(3x^2+x^3+5x-4x+x-x^2=41\)

\(3x^2+x^3+2x-x^2=41\)

\(x\left(3x+x^2\right)+x\left(2-x\right)=41\)

\(x\left(3x+x^2+2-x\right)=41\)

\(x.\left(2x+x^2+2\right)=41\)

\(x\left[x\left(x+2\right)+2\right]=41\)

Xét ước 41 là xong !