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Math question....Integral?
What is the integral of this function....
(x^2 + 4x + 8) / (x + 1)
I know it uses U substitution but I can't figure it out.
8 Answers
- RapidfireLv 79 years agoFavorite Answer
Divide the polynomials by the comparing coefficients method:
(x² + 4x + 8) / (x + 1) = Ax + B + C / (x + 1)
x² + 4x + 8 = Ax(x + 1) + B(x + 1) + C
x² + 4x + 8 = Ax² + Ax + Bx + B + C
x² + 4x + 8 = Ax² + (A + B)x + (B + C)
A = 1
A + B = 4
B = 4 - A
B = 4 - 1
B = 3
B + C = 8
C = 8 - B
C = 8 - 3
C = 5
(x² + 4x + 8) / (x + 1) = x + 3 + 5 / (x + 1)
Integrate the expression term by term using this result:
∫ (x² + 4x + 8) / (x + 1) dx = ∫ [x + 3 + 5 / (x + 1)] dx
∫ (x² + 4x + 8) / (x + 1) dx = ∫ x dx + 3 ∫ 1 dx + 5 ∫ 1 / (x + 1) dx
∫ (x² + 4x + 8) / (x + 1) dx = x² / 2 + 3x + 5ln|x + 1| + C
- 9 years ago
(x^2 + 4x + 8) / (x + 1) = x + 3 + [5 / (x + 1) ]
The integration of this function is
[(x^2) / 2] + 3x + 5 log|x + 1| + C
Source(s): self knowdge - sahsjingLv 79 years ago
(x^2 + 4x + 8) / (x + 1)
= (x^2 + x + 3x + 3 + 5) / (x + 1)
= x + 3 + 5/(x+1)
So, the integral = (1/2)x^2 + 3x + 5ln|x+1| + c
- ??????Lv 79 years ago
We divide x²+4x+8 through x+1, this gives
x+3 and 5/(x+1) as remainder
so we integrate x+3 = x²/2+3x+C
and 5/(x+1) = 5 ln( | 1+x | ) + C '
so add both we have
x²/2 + 3x + 5 ln (|1+x|) + C"
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- 9 years ago
u = x + 1
du = dx
x = u - 1
(x^2 + 4x + 8) * dx / (x + 1) =>
((u - 1)^2 + 4 * (u - 1) + 8) * du / u =>
(u^2 - 2u + 1 + 4u - 4 + 8) * du / u =>
(u^2 + 2u + 5) * du / u =>
u * du + 2 * du + 5 * du/u
Integrate:
(1/2) * u^2 + 2u + 5 * ln|u| + C =>
(1/2) * (x + 1)^2 + 2 * (x + 1) + 5 * ln|x + 1| + C =>
(1/2) * (x^2 + 2x + 1) + 2x + 2 + 5 * ln|x + 1| + C =>
(1/2) * x^2 + x + (1/2) + 2x + 2 + 5 * ln|x + 1| + C =>
(1/2) * x^2 + 3x + 5 * ln|x + 1| + (5/2) + C =>
(1/2) * x^2 + 3x + 5 * ln|x + 1| + C =>
(1/2) * (x^2 + 6x + 10 * ln|x + 1|) + C
- MechEng2030Lv 79 years ago
∫(x² + 4x + 8)/(x + 1) dx
∫((x + 2)² + 4)/(x + 1) dx
∫((x + 1)² + 2(x + 1) + 5)/(x + 1) dx
∫(x + 1) dx + ∫2 dx + ∫5/(x + 1) dx
= x²/2 + 3x + 5*ln|x + 1| + C
- ?Lv 44 years ago
Eh... neither... yet i guess i will choose English. I used to love English extra yet extreme college made it boring. -_- yet I nevertheless love writing as a interest (and hate math, even inspite of the actuality that i'm no longer undesirable at it) so i will purely say English.
- 9 years ago
divide the equation first. then you get x+3 + 5/x+1, then take the integral.
I got x²/2 + 3x + 5ln |x+1| +c.
if u have any questions feel free to ask :)
Source(s): ma cute lil brain