\(\frac{1}{2}x^2\left(6x-3\right)-x\left(x^2+\frac{1}{2}\right)+\frac{1}{2}\left(x+4\right)\)
\(=\frac{1}{2}x^2.6x+\frac{1}{2}x^2.\left(-3\right)+\left(-x\right).x^2+\left(-x\right).\frac{1}{2}+\frac{1}{2}.x+\frac{1}{2}.4\)
\(=3x^3-\frac{3}{2}x^2-x^3-\frac{1}{2}x+\frac{1}{2}x+2\)
\(=\left(3x^3-x^3\right)-\frac{3}{2}x^2+\left(-\frac{1}{2}x+\frac{1}{2}x\right)+2\)
\(=2x^3-\frac{3}{2}x^2+2\)
\(a,\)\(\frac{1}{2}x^2\left(6x-3\right)-x\left(x^2+\frac{1}{2}\right)+\frac{1}{2}\left(x+4\right)\)
\(=3x^3-\frac{3}{2}x^2-x^3-\frac{1}{2}x+\frac{1}{2}x+2\)
\(=2x^3-\frac{3}{2}x^2+2\)
\(b,\)\(2x\left(3x^3-x\right)-4x^2\left(x-x^2+1\right)+\left(x-3x^2\right)x\)
\(=6x^4-2x^2-4x^3+4x^4-4x^2+x^2-3x^3\)
\(=10x^4-7x^3-5x^2\)
\(\frac{1}{2}x^2.\left(6x-3\right)-x\left(x^2+\frac{1}{2}\right)+\frac{1}{2}\left(x+4\right)\)
\(=3x^3-\frac{3}{2}x^2-x^3-\frac{1}{2}x+\frac{1}{2}x+2\)
\(=2x^3-\frac{3}{2}x^2+2\)
\(2x\left(3x^3-x\right)-4x^2\left(x-x^2+1\right)+\left(x-3x^2\right)x\)
\(=6x^4-2x^2-4x^3+4x^4-4x^2+x^2-3x^3\)
\(=10x^4-7x^3-5x^2\)
\(2x\left(3x^3-x\right)-4x^2\left(x-x^2+1\right)+\left(x-3x^2\right)x\)
\(=2x.3x^3+2x.\left(-x\right)+\left(-4x^2\right).x+\left(-4x^2\right).\left(-x^2\right)+\left(-4x^2\right).1+x.\left(-x\right)+\left(-3x^2\right).x\)
\(=6x^4-2x^2-4x^3+4x^4-4x^2-x^2-3x^3\)
\(=\left(6x^4-4x^4\right)+\left(-2x^2-4x^2-x^2\right)+\left(-4x^3-3x^3\right)\)
\(=2x^4-7x^2-7x^3\)
CTV A4_Henry câu 2 chỗ dấu bằng số 2 chỗ \(x.\left(-x\right)\) sai nhé! Đáng phái \(x.x\)
Sr :v Câu thứ 2 tớ làm sai, giờ làm lại
\(2x\left(3x^3-x\right)-4x^2\left(x-x^2+1\right)+\left(x-3x^2\right)x\)
\(=2x.3x^3+2x.\left(-x\right)+\left(-4x^2\right).x+\left(-4x^2\right).\left(-x^2\right)+\left(-4x^2\right).1+x.x+\left(-3x^2\right).x\)
\(=6x^4-2x^2-4x^3+4x^4-4x^2+x^2-3x^3\)
\(=\left(6x^4+4x^4\right)+\left(-2x^2-4x^2+x^2\right)+\left(-4x^3-3x^3\right)\)
\(=10x^4-7x^2-7x^3\)
