\(2.\)
\(1.\left(x+2\right)\left(3x-4\right)+\left(x-3\right)^2=3x^2+2x-8+x^2-6x+9=4x^2-4x+1.\)
\(2.\left(2x-3\right)\left(2x+3\right)-4\left(x^2-2\right)=4x^2-9-4x^2+8=-1.\)
\(3.\left(x-2\right)^2-\left(3-x\right)\left(2-x\right)=x^2-4x+4-6+5x-x^2\)
\(=x-2.\)
\(4.\left(3x-1\right)^2-\left(3x+1\right)\left(3x+4\right)=9x^2-6x+1-9x^2-15x-4\)
\(=-21x-3.\)
Bài 1:
1: \(\Leftrightarrow x^2+2x+1-x^2+4x-4=4\)
=>6x-3=4
=>x=7/6
2: \(\Leftrightarrow x^2+4x+4+9-3x=3\)
\(\Leftrightarrow x^2+x+10=0\)
hay \(x\in\varnothing\)
3: \(\Leftrightarrow x^2-6x+9-x^2+16=0\)
=>-6x=-25
hay x=25/6
4: \(\Leftrightarrow4x^2-4x+1-2\left(2x^2-8x-x+4\right)=0\)
\(\Rightarrow4x^2-4x+1-4x^2+18x-8=0\)
=>14x-7=0
hay x=1/2
