Question

Rút gọn :

a,{x+2}.{x^2-2x+4}-{x^3+1}

b,{3x^2-6x}.3x+{3x-1}^2.{3x-1}

Answer 1

a) \(\left(x+2\right)\left(x^2-2x+4\right)-\left(x^3+1\right)\)\(=x^3-2^3-x^3-1=-8-1=-9\)

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

\(=\left(9x^3-18x^2\right)+\left(3x-1\right)^3\)

\(=9x^3-18x^2+27x^3-1\)

\(=36x^3-18x^2-1\)

Answer 2

a, (x+2).(x^2-2x+4)-(x^3+1)

= (x+2).(x^2-2x+2^2)-(x^3+1)

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

= x^3+2^3-x^3-1

= x^3+8-x^3-1

=7

Answer 3

a, (x+2)(x² -2x+4) - (x³ +1)

= x³ +2³ -(x³ +1)

= x³ +8 -x³ - 1

=7

b,(3x² -6x).3x +(3x-1)² .(3x-1)

= 9x³ - 18x² +(3x-1)³

= 9x³ - 18x² + 27x³ -27x² +9x - 1

= 36x³ -45x² +9x - 1

Answer 4

b, (3x^2-6x).3x+(3x-1)^2.(3-1)

= (9x^3-18x^2)+ (9x^2-1).(3x-1)

= 9x^3-18x^2+27x^3-3x-9x^2+1

= 36x^3 - 27x^2 -3x+1