đề bài : rút gọn đa thức rồi cộng A = – 5x^3 + 6x^2 – 9x^3 – 7x^2 – x +12 B= -6x^3 – 7x^2 – 6x^2 – x^3 + 7x^2 – 12x -x

0 bình luận về “đề bài : rút gọn đa thức rồi cộng A = – 5x^3 + 6x^2 – 9x^3 – 7x^2 – x +12 B= -6x^3 – 7x^2 – 6x^2 – x^3 + 7x^2 – 12x -x”

1. `A = – 5x^3 + 6x^2 – 9x^3 – 7x^2 – x +12`

   `A = (- 5x^3- 9x^3) + (6x^2 – 7x^2) – x +12`

   `A = -14x^3-x^2 – x +12`

   `B= -6x^3 – 7x^2 – 6x^2 – x^3 + 7x^2 – 12x -x`

   `B= (-6x^3- x^3)+ (- 7x^2 – 6x^2+ 7x^2 ) +(- 12x -x)`

   `B=-7x^3- 6x^2-13x`

   `A+B=(-14x^3-x^2 – x +12)+(-7x^3- 6x^2-13x)`

   `A+B=-14x^3-x^2 – x +12-7x^3- 6x^2-13x`

   `A+B=(-14x^3-7x^3)+(-x^2- 6x^2)+( – x-13x) +12`

   `A+B=-21x^3-7x^2-14x +12`

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2. BÀI LÀM :

    $A$ $=$ $-5x^{3}$ + $6x^{2}$ – $9x^{3}$ – $7x^{2}$ – $x$ + $12$

   $=$ ($-5x^{3}$- $9x^{3}$)+($6x^{2}$ – $7x^{2}$)+($-x$) + ($-12$) 

   = $-14^3$ – $1x^2$ – $x$ + $12$

   $B$ = $-6x^3$ – $7x^2$ – $6x^2$ – $x^3$ + $7x^2$ – $12x$ – $x$

   = ( $-6x^3$ – $x^3$ ) + ( $-7x^2$ – $6x^2$ + $7x^2$ ) + (-12x – x)

   = $-7x^3$ – $6x^2$ – $13x$

   $*$

   $A+B$ = ($-14x^3$ – $1x^2$ – x + 12 ) + ( $-7x^3$ – $6x^2$ – 13x )

   = $ -14^3$ –  $1x^2$ – x + 12 – $7x^3$ – $6x^2$ – 13x

   = $(-14x^3 – 7x^3)$ + $(-1x^2-6x^2)$ + (-x-13x) + (12)

   = $-21x^3$ – $7x^2$ -14x +12

   Chúc bạn học tốt :”)

   #nocopy

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