Question

Tính 

a/( 5x - 2 )^2 - 2 . ( 3x - 1 )^2

b/( 5x + x^3 + 2x^4 - 2 - 3x^2 ) : ( x^2 + 1 - x)

Answer 1

a.

\(\left(5x-2\right)^2-2\left(3x-1\right)^2=\left(25x^2-20x+4\right)-2\left(9x^2-6x+1\right)\)

\(=25x^2-20x+4-18x^2+12x-2\)

\(=7x^2-8x+2\)

b.

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

\(=\left[\left(2x^4-2x^3+2x^2\right)+\left(3x^3-3x^2+3x\right)-\left(2x^2-2x+2\right)\right]:\left(x^2-x+1\right)\)

\(=\left[2x^2\left(x^2-x+1\right)+3x\left(x^2-x+1\right)-2\left(x^2-x+1\right)\right]:\left(x^2-x+1\right)\)

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

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