Question

Tìm x

a)2x(x+3)-3(x^2+1)=x+1-x(x-2)

b)3x(x-2)-x(1+3x)=14

c)2x(x-5)-x(3+2x)=26

giải rõ chi tiết cho em với ạ

em chân thành cảm ơn

Answer 1

a) Ta có: \(2x\left(x+3\right)-3\left(x^2+1\right)=x+1-x\left(x-2\right)\)

\(\Leftrightarrow2x^2+6x-3x^2-3=x+1-x^2+2x\)

\(\Leftrightarrow-x^2+6x-3=-x^2+3x+1\)

\(\Leftrightarrow-x^2+6x-3+x^2-3x-1=0\)

\(\Leftrightarrow3x-4=0\)

\(\Leftrightarrow3x=4\)

\(\Leftrightarrow x=\frac{4}{3}\)

Vậy: \(S=\left\{\frac{4}{3}\right\}\)

b) Ta có: \(3x\left(x-2\right)-x\left(1+3x\right)=14\)

\(\Leftrightarrow3x^2-6x-x-3x^2-14=0\)

\(\Leftrightarrow-7x-14=0\)

\(\Leftrightarrow-7x=14\)

hay x=-2

Vậy: S={-2}

c) Ta có: \(2x\left(x-5\right)-x\left(3+2x\right)=26\)

\(\Leftrightarrow2x^2-10x-3x-2x^2=26\)

\(\Leftrightarrow-13x=26\)

hay x=-2

Vậy: S={-2}