Integral Examples
**Problem:** Calculate the following integrals step-by-step.
1. \( \int x^3 \, dx \)
2. \( \int 7x^{\frac{9}{3}} \, dx = \int 7x^3 \, dx \)
3. \( \int (27x^7 + 3x^5 - 24x^3) \, dx \)
4. \( \int x^2 (x^3 + 5x^2 - 3x + \sqrt{3}) \, dx \)
5. \( \int (10x^3 + 5)^6 \, dx \)
6. \( \int (x^3 - 7)^8 (3x^2) \, dx \)
7. \( \int (x^3 + 6x)^5 (3x^2 + 6) \, dx \)
8. \( \int (x^2 - 2)^{11} x \, dx \)
9. \( \int (5x^2 + 1)(5x^3 + 3x - 8)^6 \, dx \)
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### Step 1
Integral of \( x^3 \):
$$ \int x^3 \, dx = \frac{x^{3+1}}{3+1} + C = \frac{x^4}{4} + C $$
### Step 2
Integral of \( 7x^3 \):
$$ \int 7x^3 \, dx = 7 \int x^3 \, dx = 7 \cdot \frac{x^4}{4} + C = \frac{7x^4}{4} + C $$
### Step 3
Integral of \( 27x^7 + 3x^5 - 24x^3 \):
$$ \int (27x^7 + 3x^5 - 24x^3) \, dx = 27 \cdot \frac{x^8}{8} + 3 \cdot \frac{x^6}{6} - 24 \cdot \frac{x^4}{4} + C $$
Simplify:
$$ = \frac{27x^8}{8} + \frac{3x^6}{6} - 6x^4 + C = \frac{27x^8}{8} + \frac{x^6}{2} - 6x^4 + C $$
### Step 4
Expand the integrand:
$$ x^2 (x^3 + 5x^2 - 3x + \sqrt{3}) = x^5 + 5x^4 - 3x^3 + x^2 \sqrt{3} $$
Integral:
$$ \int (x^5 + 5x^4 - 3x^3 + x^2 \sqrt{3}) \, dx = \frac{x^6}{6} + 5 \cdot \frac{x^5}{5} - 3 \cdot \frac{x^4}{4} + \sqrt{3} \cdot \frac{x^3}{3} + C $$
Simplify:
$$ = \frac{x^6}{6} + x^5 - \frac{3x^4}{4} + \frac{\sqrt{3} x^3}{3} + C $$
### Step 5
Integral of \( (10x^3 + 5)^6 \):
Use substitution: let \( u = 10x^3 + 5 \), then \( du = 30x^2 dx \).
Since no \( x^2 \) term outside, integral cannot be simplified directly without more info.
Assuming the problem is \( \int (10x^3 + 5)^6 (30x^2) dx \), then:
$$ \int u^6 \, du = \frac{u^7}{7} + C = \frac{(10x^3 + 5)^7}{7} + C $$
### Step 6
Integral of \( (x^3 - 7)^8 (3x^2) \):
Let \( u = x^3 - 7 \), then \( du = 3x^2 dx \).
Integral becomes:
$$ \int u^8 \, du = \frac{u^9}{9} + C = \frac{(x^3 - 7)^9}{9} + C $$
### Step 7
Integral of \( (x^3 + 6x)^5 (3x^2 + 6) \):
Let \( u = x^3 + 6x \), then \( du = (3x^2 + 6) dx \).
Integral becomes:
$$ \int u^5 \, du = \frac{u^6}{6} + C = \frac{(x^3 + 6x)^6}{6} + C $$
### Step 8
Integral of \( (x^2 - 2)^{11} x \):
Let \( u = x^2 - 2 \), then \( du = 2x dx \).
Rewrite integral:
$$ \int (x^2 - 2)^{11} x \, dx = \frac{1}{2} \int u^{11} \, du = \frac{1}{2} \cdot \frac{u^{12}}{12} + C = \frac{(x^2 - 2)^{12}}{24} + C $$
### Step 9
Integral of \( (5x^2 + 1)(5x^3 + 3x - 8)^6 \):
Let \( u = 5x^3 + 3x - 8 \), then
$$ du = (15x^2 + 3) dx = 3(5x^2 + 1) dx $$
Rewrite integral:
$$ \int (5x^2 + 1)(5x^3 + 3x - 8)^6 \, dx = \frac{1}{3} \int u^6 \, du = \frac{1}{3} \cdot \frac{u^7}{7} + C = \frac{(5x^3 + 3x - 8)^7}{21} + C $$
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**Final answers:**
1. \( \frac{x^4}{4} + C \)
2. \( \frac{7x^4}{4} + C \)
3. \( \frac{27x^8}{8} + \frac{x^6}{2} - 6x^4 + C \)
4. \( \frac{x^6}{6} + x^5 - \frac{3x^4}{4} + \frac{\sqrt{3} x^3}{3} + C \)
5. \( \frac{(10x^3 + 5)^7}{7} + C \) (assuming integrand includes \(30x^2\))
6. \( \frac{(x^3 - 7)^9}{9} + C \)
7. \( \frac{(x^3 + 6x)^6}{6} + C \)
8. \( \frac{(x^2 - 2)^{12}}{24} + C \)
9. \( \frac{(5x^3 + 3x - 8)^7}{21} + C \)