Toán Thực hiện phép tính a. (x+8)(x+5) b. (x – 3)(x + 1)(x + 2) 05/08/2021 By Hadley Thực hiện phép tính a. (x+8)(x+5) b. (x – 3)(x + 1)(x + 2)
`a. (x – 8)(x+5)` `= x.x + x.5 + (-8).x + (-8).5` `= x^2 + 5x – 8x – 40` `= x^2 – 3x – 40` `b. (x – 3)(x + 1)(x + 2)` `= (x^2-2x-3)(x+2)` `=x3+2x^2-2x^2-4x-3x-6` `= x^3-7x-6` Trả lời
a) $(x+8)(x+5)$ $=x^2+13x+40$ b) $(x-3)(x+1)(x+2)$ $=(x-3)(x^2+3x+2)$ $=x^3+3x^2+2x-3x^2-9x-6$ $=x^3-7x-6$ Trả lời
`a. (x – 8)(x+5)`
`= x.x + x.5 + (-8).x + (-8).5`
`= x^2 + 5x – 8x – 40`
`= x^2 – 3x – 40`
`b. (x – 3)(x + 1)(x + 2)`
`= (x^2-2x-3)(x+2)`
`=x3+2x^2-2x^2-4x-3x-6`
`= x^3-7x-6`
a) $(x+8)(x+5)$
$=x^2+13x+40$
b) $(x-3)(x+1)(x+2)$
$=(x-3)(x^2+3x+2)$
$=x^3+3x^2+2x-3x^2-9x-6$
$=x^3-7x-6$