Is x + 1 a factor of x^3 + 6x^2 – 2x – 7?
A. Yes
B. No
COLLEGE ALGEBRA ~ 10 PTS?
2009-07-08 3:12 pm
回答 (7)
2009-07-08 3:20 pm
✔ 最佳答案
= (x³ + 6x² - 2x - 7)/(x + 1)= x² + 5x - 7
Answer: A. Yes it is!—there is no remainder when you divide it by x + 1.
2009-07-08 11:43 pm
..................x^2 + 5x - 7
.......________________
x + 1)x^3 + 6x^2 - 2x - 7
.........x^3 + x^2
------------------------------------
..................5x^2 - 2x
..................5x^2 + 5x
------------------------------------
..........................-7x - 7
..........................-7x - 7
------------------------------------
Therefore, x + 1 is a factor of x^3 + 6x^2 - 2x - 7.
(answer A)
.......________________
x + 1)x^3 + 6x^2 - 2x - 7
.........x^3 + x^2
------------------------------------
..................5x^2 - 2x
..................5x^2 + 5x
------------------------------------
..........................-7x - 7
..........................-7x - 7
------------------------------------
Therefore, x + 1 is a factor of x^3 + 6x^2 - 2x - 7.
(answer A)
2009-07-08 10:35 pm
x+1
let x+1 x=-1
plug in x=-1 to x^3+6x^2 – 2x – 7
f(-1)=x^3+6x^2 – 2x – 7
=(-1)^3+6(-1)^2-2(-1)-7
=-1+6+2-7
=0
therefore x^3 + 6x^2 – 2x – 7 is a factor of x+1..
A, Yes//
let x+1 x=-1
plug in x=-1 to x^3+6x^2 – 2x – 7
f(-1)=x^3+6x^2 – 2x – 7
=(-1)^3+6(-1)^2-2(-1)-7
=-1+6+2-7
=0
therefore x^3 + 6x^2 – 2x – 7 is a factor of x+1..
A, Yes//
2009-07-08 10:21 pm
OK
The answer is A - yes
(x+1)(x^2 +5x-7)
Proof
(x+1)(x^2 +5x-7) =
x^3 +5x^2 -7x +x^2 +5x -7
= x^3 +6x^2 -2x -7
Hope that helps.
The answer is A - yes
(x+1)(x^2 +5x-7)
Proof
(x+1)(x^2 +5x-7) =
x^3 +5x^2 -7x +x^2 +5x -7
= x^3 +6x^2 -2x -7
Hope that helps.
2009-07-08 10:18 pm
Using factor thereom:
f(-1) = -1 +6 +2 -7 = 0
so yes, (x+1) is a factor.
f(-1) = -1 +6 +2 -7 = 0
so yes, (x+1) is a factor.
2009-07-08 10:17 pm
A. Yes
f(-1) = -1 + 6 + 2 - 7 = 0
(This means it is a factor)
f(-1) = -1 + 6 + 2 - 7 = 0
(This means it is a factor)
2009-07-08 10:16 pm
Yes it is
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