Ta có:

\(A=\left(9x-1\right)^2+\left(1-5x\right)^2+2\left(9x-1\right)\left(1-5x\right)\)

\(=\left(9x-1+1-5x\right)^2\)

\(=4x^2\)

\(=16x^2\)

=(9x-1+1-5x)²=(4x)²=16x²

Nguyễn Việt Hoàng bị ngu à,4x²=16x²,giỏi đấy

Bài làm :

\(\left(9x-2\right)\left(x^2-5x+1\right)-x\left(x^2+11\right)\)

\(=9x^3-45x^2+9x-2x^2+10x-2-x^3-11x\)

\(=\left(9x^3-x^3\right)+\left(-45x^2-2x^2\right)+\left(9x+10x-11x\right)-2\)

\(=8x^3-47x^2+8x-2\)

Học tốt nhé

( 9x - 2 )( x² - 5x + 1 ) - x( x² + 11 )

= 9x³ - 45x² + 9x - 2x² + 10x - 2 - x³ - 11x

= 8x³ - 47x² + 8x - 2

                                                        Bài giải

\(\left(9x-2\right)\left(x^2-5x+1\right)-x\left(x^2+11\right)\)

\(=9x^3-45x^2+9x-2x^2+10x-2-x^3-11x\)

\(=8x^3-47x^2+8x-2\)

c,4x²-20x+25-4x²-20x-25+40x-1

=-1

\(a,3x\left(x-2\right)-5x\left(1-x\right)-8\left(x^2-3\right)\)

\(=3x^2-6x-5x+5x^2-8x^2+24\)

\(=\left(3x^2+5x^2-8x^2\right)+\left(-6x-5x\right)+24\)

\(=0-11x+24\)

\(=-11x+24\)

\(b,\left(7x-3\right)\left(2x+1\right)-\left(5x-2\right)\left(x+4\right)-9x^2+17x\)

\(=14x^2+7x-6x-3-5x^2-20x+2x+8-9x^2+17x\)

\(=\left(14x^2-5x^2-9x^2\right)+\left(7x-6x-20x+2x+17x\right)+\left(-3+8\right)\)

\(=0+0+5\)

\(=5\)

a: \(=\dfrac{4x\left(3x+1\right)}{\left(3x+1\right)\left(3x-1\right)}=\dfrac{4x}{3x-1}\)

b: \(=\dfrac{2\left(4x^2-4x+1\right)}{4x-30+2x}=\dfrac{4\left(2x-1\right)^2}{6x-30}=\dfrac{2\left(2x-1\right)^2}{3\left(x-5\right)}\)

d: \(=\dfrac{x\left(x-6\right)}{2\left(x-6\right)\left(x+6\right)}=\dfrac{x}{2x+12}\)

a) x (x+1) (x-1) - (x-1) (x²+x+1)= x³ - x² + x² - x - x³ + 1³

                                           = 1- x