Question

Rút gọn đa thức:

(2x-1)^2-2(2x-3)^2+4

Answer 1

( 2x - 1)² - 2( 2x - 3)² + 4

= 4x² - 4x + 1 - 2( 4x² - 12x + 9) + 4

= 4x² - 4x + 1 - 8x² + 24x - 18 + 4

= -4x² + 20x - 13

Answer 2

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

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

\(=4x^2-4x+1-8x^2+24x-18+4\)

\(=\left(4x^2-8x^2\right)+\left(24x-4x\right)-\left(18-4-1\right)\)

\(=-4x^2+20x-13\)