Tìm x biết :(đề không sai )
1.−4x(x−7)+4x(x2−5) =28x2−13
2.(4x2−5x)(3x+2)−7x(x+5) =(−4+x)(−2x+3)+12x3+2x2
3.(−4x2−3)(2x+5) −(8x−3)(−x2+2) −5x(x−6)−3x2−4
4.(x−7)(x+5)−(x−3)(x−2) =15x2(x+1)−(3x2−1) (5x2−2)−21x2
5.(x−3)(−x+10)+(x−8)(x+3)=(5x2−1)(x+3)−5x3−15x2
6.(−2x2+5)(−x+3)−x2(2x−6) =(x−1)(x+1)−(x−2)(x+4)