Question

Rút gọn:

a) (x+2)(x²-2x+4)-(18+x³)

b)(x-3)(x+3)-(x+5)(x-1)

Answer 1

ta có: a) (x+2)(x²-2x+4)-(18+x³)

=(x³+4)-(18+x³)

=x³+8-18-x³

=8-18

=-10

b)(x-3)(x+3)-(x+5)(x-1)=(x²-9)-(x²-x+5x-5)

=(x²-9)-(x²+4x-5)

=x²-9-x²-4x+5

=-9-4x+5

=-4-4x

=4(-1-x)

Answer 2

a) (x+2)(x²-2x+4)-(18+x³)=(x³+4)-(18+x³)

=x³+4-18-x³

=4-18

=-14

b)(x-3)(x+3)-(x+5)(x-1)=(x²-9)-(x²-x+5x-5)

=(x²-9)-(x²+4x-5)

=x²-9-x²-4x+5

=-9-4x+5

=-4-4x

=4(-1-x)

Answer 3

* \(\left(x+2\right)\left(x^2-2x+4\right)-\left(18+x^3\right)\)

\(=x^3+2^3-18-x^3\)

\(=8-18=-10\)

* \(\left(x-3\right)\left(x+3\right)-\left(x+5\right)\left(x-1\right)\)

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

\(=x^2-9-x^2+x-5x+5\)

\(=-4x-4=-4.\left(x+1\right)\)

(Nếu đúng thì k cho mình với nhé nhe!)

Answer 4

làm lại, lúc nãy mình nhầm 1 chút:

a) (x+2)(x²-2x+4)-(18+x³)=(x³+4)-(18+x³)

=x³+8-18-x³

=8-18

=-10

b)(x-3)(x+3)-(x+5)(x-1)=(x²-9)-(x²-x+5x-5)

=(x²-9)-(x²+4x-5)

=x²-9-x²-4x+5

=-9-4x+5

=-4-4x

=4(-1-x)