Math Problem Statement

Evaluate. Integral from negative 1 to 4 left parenthesis 4 x squared minus 3 x plus 4 right parenthesis dx

Solution

To evaluate the definite integral of 14(4x23x+4)dx\int_{-1}^4 (4x^2 - 3x + 4) \, dx, follow these steps:

Step 1: Compute the indefinite integral

The integrand is 4x23x+44x^2 - 3x + 4. The integral of each term is:

4x2dx=4x33,3xdx=3x22,4dx=4x.\int 4x^2 \, dx = \frac{4x^3}{3}, \quad \int -3x \, dx = -\frac{3x^2}{2}, \quad \int 4 \, dx = 4x.

Thus, the indefinite integral is:

(4x23x+4)dx=4x333x22+4x+C.\int (4x^2 - 3x + 4) \, dx = \frac{4x^3}{3} - \frac{3x^2}{2} + 4x + C.

Step 2: Evaluate the definite integral

The definite integral is:

14(4x23x+4)dx=[4x333x22+4x]14.\int_{-1}^4 (4x^2 - 3x + 4) \, dx = \left[ \frac{4x^3}{3} - \frac{3x^2}{2} + 4x \right]_{-1}^4.

Evaluate at x=4x = 4:

4(4)333(4)22+4(4)=46433162+16=256324+16.\frac{4(4)^3}{3} - \frac{3(4)^2}{2} + 4(4) = \frac{4 \cdot 64}{3} - \frac{3 \cdot 16}{2} + 16 = \frac{256}{3} - 24 + 16.

Simplify:

25638=2563243=2323.\frac{256}{3} - 8 = \frac{256}{3} - \frac{24}{3} = \frac{232}{3}.

Evaluate at x=1x = -1:

4(1)333(1)22+4(1)=4(1)33(1)24=43324.\frac{4(-1)^3}{3} - \frac{3(-1)^2}{2} + 4(-1) = \frac{4(-1)}{3} - \frac{3(1)}{2} - 4 = -\frac{4}{3} - \frac{3}{2} - 4.

Simplify using a common denominator of 6:

43=86,32=96,4=246.-\frac{4}{3} = -\frac{8}{6}, \quad -\frac{3}{2} = -\frac{9}{6}, \quad -4 = -\frac{24}{6}.

Combine:

8696246=416.-\frac{8}{6} - \frac{9}{6} - \frac{24}{6} = -\frac{41}{6}.

Step 3: Subtract the results

The definite integral is:

2323(416)=2323+416.\frac{232}{3} - \left(-\frac{41}{6}\right) = \frac{232}{3} + \frac{41}{6}.

Use a common denominator of 6:

2323=4646,4646+416=5056.\frac{232}{3} = \frac{464}{6}, \quad \frac{464}{6} + \frac{41}{6} = \frac{505}{6}.

Final Answer:

14(4x23x+4)dx=5056.\int_{-1}^4 (4x^2 - 3x + 4) \, dx = \frac{505}{6}.

Would you like a detailed breakdown of any step?


  1. What is the process for finding indefinite integrals?
  2. How do you determine common denominators in fractional arithmetic?
  3. Why is a common denominator important in subtracting definite integrals?
  4. What role do boundaries x=1x = -1 and x=4x = 4 play in definite integrals?
  5. Can integrals of polynomials always be solved directly like this?

Tip: Always double-check constants of integration for indefinite integrals when solving symbolically.

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Math Problem Analysis

Mathematical Concepts

Calculus
Definite Integrals
Polynomial Integration

Formulas

Integral of a polynomial: ∫ax^n dx = (a/(n+1))x^(n+1) + C
Definite integral: ∫[a,b] f(x) dx = F(b) - F(a), where F'(x) = f(x)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12 or introductory college-level calculus