Đáp án+Giải thích các bước giải
a. x.( $2x^{2}$ - 3) -$x^{2}$ . ( 5x + 1 ) + $x^{2}$
= x . $2x^{2}$ - 3x - $x^{2.}$. 5x - $x^{2}$ + $x^{2}$
= $2x^{3}$ - 3x - $5x^{3}$ - $x^{2}$ + $x^{2}$
= $-3x^{3}$ - 3x
b. 3x. ( x -2 ) - 5x ( 1 - x ) - 8 ( $x^{2}$ - 3 )
= 3x . x - 2.3x - 5x + 5x. x - 8. $x^{2}$ + 8 . 3
= $3x^{2}$ - 6x - 5x + $5x^{2}$ - $8x^{2}$ + 24
= -11x + 24
c. $\frac{1}{2}$ $x^{2}$ ( 6x - 3 ) - x ( $x^{2}$ + $\frac{1}{2}$ ) + $\frac{1}{2}$ ( x + 4)
= $\frac{1}{2}$ $x^{2}$ .6x - $\frac{1}{2}$$x^{2}$ . 3 - x . $x^{2}$ - x. $\frac{1}{2}$ + $\frac{1}{2}$ . x + $\frac{1}{24}$ . 4
= $3x^{3}$ - $\frac{3}{2}$$x^{2}$ - $x^{3}$ - $\frac{1}{2}$x + $\frac{1}{2}$x +2
= $2x^{3}$ - $\frac{3}{2}$ $x^{2}$ + 2
