Câu hỏi của Nguyễn Phong

Question

Cho các đa thức:

M=3x3-4x2-x+5

N=x3-2x2+5x-4

P=3x3-x2-5x+10

a)M+N+P  b)M-N-P

c)N-M-P  d)P-N-M

Bro_Jeon_Downy · Accepted Answer

a) M+N+P= 3x3-4x2-x+5+x3-2x2+5x-4+3x3-x2-5x+10

=3x3+x3+3x3-4x2-2x2-x2-x+5x-5x+5-4+10

=7x3-7x2-x+11

b)M-N-P=3x3-4x2-x+5-(x3-2x2+5x-4)-(3x3-x2-5x+10)

=3x3-4x2-x+5-x3+2x2-5x+4-3x3+x2+5x-10

=3x3-x3-3x3-4x2+2x2+x2-x-5x+5x+5+4-10

=-x3-x2-x-1

c)N-M-P=x3-2x2+5x-4-(3x3-4x2-x+5)-(3x3-x2-5x+10)

=x3-2x2+5x-4-3x3+4x2+x-5-3x3+x2+5x-10

=x3-3x3-3x3-2x2+4x2+x2+5x+x+5x-4-5-10

=-5x3+3x2+11x-19

d)P-N-M=3x3-x2-5x+10-(x3-2x2+5x-4)-(3x3-4x2-x+5)

=3x3-x2-5x+10-x3+2x2-5x+4-3x3+4x2+x-5

=3x3-x3-3x3-x2+2x2+4x2-5x-5x+x+10+4-5

=-x3+5x2-9x+9Câu trả lời: a) M+N+P= 3x3-4x2-x+5+x3-2x2+5x-4+3x3-x2-5x+10