1. Problem a) Find $$\int \frac{6}{x^2 + 3} \, dx$$
Formula: $$\int \frac{dx}{x^2 + a^2} = \frac{1}{a} \arctan \frac{x}{a} + C$$
Here, $a^2 = 3$, so $a = \sqrt{3}$.
Step 1: Factor out the constant 6:
$$\int \frac{6}{x^2 + 3} \, dx = 6 \int \frac{1}{x^2 + (\sqrt{3})^2} \, dx$$
Step 2: Apply the formula:
$$6 \times \frac{1}{\sqrt{3}} \arctan \frac{x}{\sqrt{3}} + C = \frac{6}{\sqrt{3}} \arctan \frac{x}{\sqrt{3}} + C$$
Step 3: Simplify the coefficient:
$$\frac{6}{\sqrt{3}} = 2 \sqrt{3}$$
Final answer a):
$$2 \sqrt{3} \arctan \frac{x}{\sqrt{3}} + C$$
2. Problem b) Find $$\int \sin \left( \frac{x}{2} \right) dx$$
Formula: $$\int \sin(kx) dx = -\frac{1}{k} \cos(kx) + C$$
Here, $k = \frac{1}{2}$.
Step 1: Apply the formula:
$$-\frac{1}{\frac{1}{2}} \cos \left( \frac{x}{2} \right) + C = -2 \cos \left( \frac{x}{2} \right) + C$$
Final answer b):
$$-2 \cos \left( \frac{x}{2} \right) + C$$
3. Problem c) Find $$\int \frac{1}{2x - 1} dx$$
Formula: $$\int \frac{1}{ax + b} dx = \frac{1}{a} \ln |ax + b| + C$$
Here, $a=2$, $b=-1$.
Step 1: Apply the formula:
$$\frac{1}{2} \ln |2x - 1| + C$$
Final answer c):
$$\frac{1}{2} \ln |2x - 1| + C$$
4. Problem d) Find $$\int \frac{x}{2 - x^2} dx$$
Rewrite denominator: $$2 - x^2 = -(x^2 - 2)$$
Step 1: Substitute $u = 2 - x^2$, then $du = -2x dx$ or $-\frac{1}{2} du = x dx$
Step 2: Rewrite integral:
$$\int \frac{x}{2 - x^2} dx = \int \frac{x dx}{u} = \int \frac{-\frac{1}{2} du}{u} = -\frac{1}{2} \int \frac{1}{u} du$$
Step 3: Integrate:
$$-\frac{1}{2} \ln |u| + C = -\frac{1}{2} \ln |2 - x^2| + C$$
Final answer d):
$$-\frac{1}{2} \ln |2 - x^2| + C$$
5. Problem e) Find $$\int \frac{4x - 10}{x^2 - 5x + 1} dx$$
Step 1: Notice numerator is derivative of denominator:
$$\frac{d}{dx} (x^2 - 5x + 1) = 2x - 5$$
Rewrite numerator:
$$4x - 10 = 2(2x - 5)$$
Step 2: Split integral:
$$\int \frac{4x - 10}{x^2 - 5x + 1} dx = 2 \int \frac{2x - 5}{x^2 - 5x + 1} dx$$
Step 3: Use substitution $u = x^2 - 5x + 1$, $du = (2x - 5) dx$
Step 4: Integral becomes:
$$2 \int \frac{du}{u} = 2 \ln |u| + C = 2 \ln |x^2 - 5x + 1| + C$$
Final answer e):
$$2 \ln |x^2 - 5x + 1| + C$$
6. Problem f) Find $$\int \tan 3x \, dx$$
Formula: $$\int \tan(kx) dx = -\frac{1}{k} \ln |\cos(kx)| + C$$
Here, $k=3$.
Step 1: Apply formula:
$$-\frac{1}{3} \ln |\cos 3x| + C$$
Final answer f):
$$-\frac{1}{3} \ln |\cos 3x| + C$$
Integral Calculations B3807A
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