Question

giải bài 28,29,30,31

Answer 1

28

1) \(x^3+3^3=\left(x+3\right)\left(x^2-3x+9\right)\)

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

3) \(x^3+8=\left(x+2\right)\left(x^2+2x+4\right)\)

4) \(x^3-64=\left(x-4\right)\left(x^2+4x+16\right)\)

5) \(1000-y^3=\left(10-y\right)\left(100+10y+y^2\right)\)

6) \(125-8x^3=\left(5-2x\right)\left(25+10x+4x^2\right)\)

7) \(x^3+27y^3=\left(x+3y\right)\left(x^2-3xy+9y^2\right)\)

8) \(8x^3+27y^3=\left(2x+3y\right)\left(4x^2-6xy+9x^2\right)\)

Answer 2

Bài 31:

a: Ta có: \(\left(x+3\right)\left(x-4\right)+\left(x-4\right)^2\)

\(=x^2-x-12+x^2-8x+16\)

\(=2x^2-9x+4\)

b: Ta có: \(\left(x-2\right)^3+\left(x^2+3\right)\left(x-3\right)\)

\(=x^3-6x^2+12x-8+x^3-3x^2+3x-9\)

\(=2x^3-9x^2+15x-17\)

c: Ta có: \(x\left(x-14\right)-10\left(x-1\right)^2\)

\(=x^2-14x-10x^2+20x-10\)

\(=-9x^2+6x-10\)