Câu hỏi của Đặng Vũ Hoài Anh

Question

Bài 1: Cho các đa thức:

A=4(x-5)-x2(x+1)-x3(x-3)-(x-4+x2)

B= -3(x2-x+1)-2(4-x2)-6(x+1)-x4-x3

C= -(x4+3x2-2)-x2(5-x)+3(x-1)

Rút gọn A,B,C

Tính A-B,B-C,C-A

Vũ Như Quỳnh · Accepted Answer

A =   $4\left(x-5\right)-x^2\left(x+1\right)-x^3\left(x-3\right)-\left(x-4+x^2\right)$

A =   $4x-20-x^3-x^2-x^4+3x^3-x+4-x^2$

A =   $-x^3-3x^3-x^2+x^2-x^4+4x-x-20+4$

A =    $-4x^3-x^4+4x-16$

B =   $-3\left(x^2-x+1\right)-2\left(4-x^2\right)-6\left(x+1\right)-x^4-x^3$

B =    $-3x^2+3x-3-8+2x^2-6x-6-x^4-x^3$

B =    $-x^4-x^3-3x^2-2x^2+3x-6x-3-8-6$

B =     $-x^4-x^3-5x^2-3x-17$

C =  $-\left(x^4+3x^2-2\right)-x^2\left(5-x\right)+3\left(x-1\right)$

C =   $-x^4-3x^2+2-5x^2+x^3+3x-3$

C =   $-x^4+x^3-3x^2+5x^2+3x+2-3$

C =   $-x^4+x^3-2x^2+3x-1$

#YiinCâu trả lời: A =   $4\left(x-5\right)-x^2\left(x+1\right)-x^3\left(x-3\right)-\left(x-4+x^2\right)$

A =   $4x-20-x^3-x^2-x^4+3x^3-x+4-x^2$

A =   $-x^3-3x^3-x^2+x^2-x^4+4x-x-20+4$

A =    $-4x^3-x^4+4x-16$

B =   $-3\left(x^2-x+1\right)-2\left(4-x^2\right)-6\left(x+1\right)-x^4-x^3$

B =    $-3x^2+3x-3-8+2x^2-6x-6-x^4-x^3$

B =    $-x^4-x^3-3x^2-2x^2+3x-6x-3-8-6$

B =     $-x^4-x^3-5x^2-3x-17$

C =  $-\left(x^4+3x^2-2\right)-x^2\left(5-x\right)+3\left(x-1\right)$

C =   $-x^4-3x^2+2-5x^2+x^3+3x-3$

C =   $-x^4+x^3-3x^2+5x^2+3x+2-3$

C =   $-x^4+x^3-2x^2+3x-1$

#Yiin

Phạm Ngân Hà · Answer

$A=4x-20-x^3-x-x^4+3x^3-x+4-x^2$

$=-x^4+2x^3-x^2+2x-16$

$B=-3x^2+3x-3-8+2x^2-6x-6-x^4-x^3$

$=-x^4-x^3-x^2-3x-17$

$C=-x^4-3x^2+2-5x^2+x^3+3x-3$

$=-x^4+x^3-8x^2+3x-1$

Từ đó có:

$A-B=-x^4+2x^3-x^2+2x-16-\left(-x^4-x^3-x^2-3x-17\right)$

$=-x^4+2x^3-x^2+2x-16+x^4+x^3+x^2+3x+17$$=3x^3+5x+1$

$B-C=-x^4-x^3-x^2-3x-17-\left(-x^4+x^3-8x^2+3x-1\right)$

$=-x^4-x^3-x^2-3x-17+x^4-x^3+8x^2-3x+1$

$=-2x^3+7x^2-6x-16$

$C-A=-x^4+x^3-8x^2+3x-1-\left(-x^4+2x^3-x^2-2x-16\right)$

$=-x^4+x^3-8x^2+3x-1+x^4-2x^3+x^2+2x+16$

$=-x^3-7x^2+5x+15$Câu trả lời: $A=4x-20-x^3-x-x^4+3x^3-x+4-x^2$