Cho : P(x) = 2x^3 – 2x – 5 Q(x) = –x^3 + x^2 + 1 – x. Tính : a. P(x) +Q(x); b. P(x) − Q(x). 23/08/2021 Bởi Sarah Cho : P(x) = 2x^3 – 2x – 5 Q(x) = –x^3 + x^2 + 1 – x. Tính : a. P(x) +Q(x); b. P(x) − Q(x).
Đáp án: a, $P(x) + Q(x) = 2x^3 – 2x – 5 – x^3 + x^2 + 1 – x$ $= (2x^3 – x^3) + x^2 – (2x + x ) – (5 – 1 )$ $= x^3 – 3x – 4 $ b,$ P(x) – Q(x) = 2x^3 – 2x – 5 + x^3 – x^2 – 1+ x$ $= (2x^3 + x^3) – (2x – x ) – x^2 – (5+1)$ $= 3x^3 – x – x^2 – 6$ Giải thích các bước giải: Bình luận
Đáp án: a) `P(x) +Q(x)= 2x^3 – 2x – 5+(–x^3 + x^2 + 1 – x)` `P(x) +Q(x)=(2x^3–x^3)+x^2+(-2x-x)+(-5+1)` `P(x) +Q(x)=x³+x²-3x-4` b) `P(x) − Q(x)=2x^3 – 2x – 5-(–x^3 + x^2 + 1 – x)` `P(x) − Q(x)=2x^3 – 2x – 5+x³-x²-1+x` `P(x) − Q(x)=(2x^3+x³)-x²+(-2x+x)+(-5-1)` `P(x) − Q(x)=3x³-x²-x-6` Bình luận
Đáp án:
a, $P(x) + Q(x) = 2x^3 – 2x – 5 – x^3 + x^2 + 1 – x$
$= (2x^3 – x^3) + x^2 – (2x + x ) – (5 – 1 )$
$= x^3 – 3x – 4 $
b,$ P(x) – Q(x) = 2x^3 – 2x – 5 + x^3 – x^2 – 1+ x$
$= (2x^3 + x^3) – (2x – x ) – x^2 – (5+1)$
$= 3x^3 – x – x^2 – 6$
Giải thích các bước giải:
Đáp án:
a)
`P(x) +Q(x)= 2x^3 – 2x – 5+(–x^3 + x^2 + 1 – x)`
`P(x) +Q(x)=(2x^3–x^3)+x^2+(-2x-x)+(-5+1)`
`P(x) +Q(x)=x³+x²-3x-4`
b)
`P(x) − Q(x)=2x^3 – 2x – 5-(–x^3 + x^2 + 1 – x)`
`P(x) − Q(x)=2x^3 – 2x – 5+x³-x²-1+x`
`P(x) − Q(x)=(2x^3+x³)-x²+(-2x+x)+(-5-1)`
`P(x) − Q(x)=3x³-x²-x-6`