Question

Difficulty: MediumDefinite Integrals and Area Under Curves

What is the value of the definite integral ∫12(4x3−3x2+2) dx\int_{1}^{2} (4x^3 - 3x^2 + 2) \, dx?

  1. A
    8
  2. 10Answer
  3. C
    12
  4. D
    14

Answer

10
Integrating each term yields F(x)=x4−x3+2xF(x) = x^4 - x^3 + 2x. Substituting the upper boundary gives F(2)=12F(2) = 12 and the lower boundary gives F(1)=2F(1) = 2. Calculating F(2)−F(1)F(2) - F(1) gives 12−2=1012 - 2 = 10, which is the exact value of the definite integral.

Step-by-Step Solution

1
Find the indefinite antiderivative of the integrand 4x3−3x2+24x^3 - 3x^2 + 2.
F(x)=∫(4x3−3x2+2) dx=x4−x3+2xF(x) = \int (4x^3 - 3x^2 + 2) \, dx = x^4 - x^3 + 2x
Apply the power rule of integration ∫xndx=xn+1n+1\int x^n dx = \frac{x^{n+1}}{n+1} to each term.
2
Evaluate the antiderivative at the upper limit x=2x = 2.
F(2)=(2)4−(2)3+2(2)=16−8+4=12F(2) = (2)^4 - (2)^3 + 2(2) = 16 - 8 + 4 = 12
Substitute x=2x = 2 into F(x)F(x).
3
Evaluate the antiderivative at the lower limit x=1x = 1.
F(1)=(1)4−(1)3+2(1)=1−1+2=2F(1) = (1)^4 - (1)^3 + 2(1) = 1 - 1 + 2 = 2
Substitute x=1x = 1 into F(x)F(x).
4
Subtract the lower limit value from the upper limit value.
F(2)−F(1)=12−2=10F(2) - F(1) = 12 - 2 = 10
Apply the Fundamental Theorem of Calculus: ∫abf(x)dx=F(b)−F(a)\int_{a}^{b} f(x) dx = F(b) - F(a).

Key Concept

Definite Integration of Polynomial Functions
Estimated Time:1m 30s
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