a) 5x² ( 3x² -7x+2)-15x(x-3)

=15x⁴-35x³+10x²-15x²+45x

=15x⁴-35x³-5x²+45x

c) (x+3)(x-3)(x-2)(x+1)

=(x²-9)(x²+x-2x-2)

=(x²-9)(x²-x-2)

=x⁴-x³-2x²-9x²+9x+18

=x⁴-x³-11x²+9x+18

d)(2x+1)²+(4x-1)²+2(2x+1)(4x+1)

=2x²+4x+1-16x²-8x+1

=2x²+4x+1-16x²-8x+1+16x²-4x+8x-2

=2x²+7

e) (2x²-3x)(5x²-2x+1)-10x²(x+3)

=10x⁴ -4x³+2x²-15x³+6x²-3 -10x²-30x

=10x⁴-19x³-2x²-30x-3

thanks bn nka

câu c) bn thíu dấu

Câu 1: C

Câu 2: =x(x-2)*(x+2)

Bài 1

A= (x-2)(2x-1)-2x(x+3)=2x²-x-4x+2-2x²-6x=-11x+2

Bài 1:

a) \(A=\left(x-2\right)\left(2x-1\right)-2x\left(x+3\right)\)

\(A=2x^2-x-4x+2-2x^2-6x\)

\(A=-11x+2\)

b) \(B=\left(3x-2\right)\left(2x+1\right)-\left(6x-1\right)\left(x+2\right)\)

\(B=6x^2+3x-4x-2-6x^2-12x+x+2\)

\(B=-12x\)

c) \(C=6x\left(2x+3\right)-\left(4x-1\right)\left(3x-2\right)\)

\(C=12x^2+18x-12x^2+8x+3x-2\)

\(C=29x-2\)

d) \(D=\left(2x+3\right)\left(5x-2\right)+\left(x+4\right)\left(2x-1\right)-6x\left(2x-3\right)\)

\(D=10x^2-4x+15x-6+2x^2-x+8x-4-12x^2+18x\)

\(D=36x-10\)

Bài 2: 

a: Ta có: \(2x\left(3x-5\right)\left(x+11\right)-3x\left(2x+3\right)\left(x+7\right)\)

\(=2x\left(3x^2+33x-5x-55\right)-3x\left(2x^2+14x+3x+21\right)\)

\(=6x^3+56x^2-110x-6x^2-51x^2-63x\)

\(=-117x\)

b: Ta có: \(\left(x^2+5x-6\right)\left(x-1\right)-\left(x+2\right)\left(x^2-x+1\right)-x\left(3x-10\right)\)

\(=x^3+4x^2-11x+6-\left(x^3-x^2+x+2x^2-2x+2\right)-3x^2+10x\)

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

=4

c: Ta có: \(\left(x^2+x+1\right)\left(x-1\right)-x^2\left(x+1\right)+x^2-5\)

\(=x^3-1-x^3-x^2+x^2-5\)

=-6

a/ 2x\(^{^{ }3}\)-3\(^{^{ }3}\)-2x\(^3\)-1\(^{^{ }3}\)=-28

b/x\(^{^{ }3}\)+2\(^{^{ }3}\)-x\(^3\)+2=10

c/3x\(^3\)+5\(^3\)-3x(3x\(^2\)-1)=3x\(^3\)+5\(^3\)-3x\(^3\)+3x=125+3x

d/ x\(^6\)-(x\(^3\)+1)(x\(^2\)-x+1)= x\(^6\)-(x\(^6\)-x\(^4\)+x\(^3\)+x\(^2\)-x+1)=x\(^4\)-x\(^3\)-x\(^2\)+x-1

a: Ta có: \(\left(x+5\right)^2-4x\left(2x+3\right)^2-\left(2x-1\right)\left(x+3\right)\left(x-3\right)\)

\(=x^2+10x+25-4x\left(4x^2+12x+9\right)-\left(2x-1\right)\left(x^2-9\right)\)

\(=x^2+10x+25-16x^3-48x^2-36x-2x^3+18x+x^2-9\)

\(=-18x^3-46x^2-8x+16\)

1, a,\(\left(-7x^2\right)\left(3x^2-x-2\right)\)

\(=-21x^4+7x^3+14x^2\)

\(b,\left(2x^3-3x^2-10x+3\right):\left(x-3\right)\)

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

\(=x^3+x-3x^2-3-x^3+27\)

\(=-3x^2+x+24\)

\(b,\left(2x+1\right)^2+\left(2x-1\right)^2+2\left(4x^2-1\right)\)

\(=4x^2+4x+1+4x^2-4x+1+8x^2-2\)

\(=24x^2\)

\(3,a,x^3-x^2-x+1\)

\(=x^2\left(x-1\right)-\left(x-1\right)\)

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

\(b,3x^2-7x-10\)

\(=3x^2+3x-10x-10\)

\(=3x\left(x+1\right)-10\left(x+1\right)\)

\(=\left(x+1\right)\left(3x-10\right)\)

4, a. Bn kiểm tra lại đề bài nhé

b,\(4x^2-12xy+10y^2\)

\(=\left(4x^2-12xy+9y^2\right)+y^2\)

\(=\left(2x-3y\right)^2+y^2\ge0\forall x,y\)

Bài 2:

a: \(=2x^4-x^3-10x^2-2x^3+x^2+10x=2x^3-3x^3-9x^2+10x\)

b: \(=\left(x^2-15x\right)\left(x^2-7x+3\right)\)

\(=x^4-7x^3+3x^2-15x^3+105x^2-45x\)

\(=x^4-22x^3+108x^2-45x\)

c: \(=12x^5-18x^4+30x^3-24x^2\)

d: \(=-3x^6+2.4x^5-1.2x^4+1.8x^2\)