Calculate The Indefinite Integral of Y Square Root of X
This guide explains how to calculate the indefinite integral of y = √x (∫√x dx) using calculus rules. We'll cover the formula, step-by-step solution, worked example, and common pitfalls.
What is an indefinite integral?
An indefinite integral represents the antiderivative of a function. It finds all functions whose derivative equals the original function. The result includes a constant of integration (C) because derivatives of constants are zero.
For a function f(x), the indefinite integral is written as ∫f(x) dx. The notation means "the antiderivative of f(x) with respect to x."
Integral of √x (∫√x dx)
The integral of the square root of x is a fundamental calculus problem. The square root function can be written as x^(1/2), so we'll use power rule integration.
The result is (2/3)x^(3/2) + C, where C is the constant of integration. This means the antiderivative of √x is (2/3)x^(3/2) plus any constant.
Step-by-step solution
- Rewrite √x as x^(1/2)
- Apply the power rule for integration: ∫x^n dx = (x^(n+1))/(n+1) + C
- Substitute n = 1/2: ∫x^(1/2) dx = (x^(1/2 + 1))/(1/2 + 1) + C
- Simplify the exponents: (x^(3/2))/(3/2) + C
- Simplify the fraction: (2/3)x^(3/2) + C
Remember: The constant of integration (C) is essential because derivatives of constants are zero. Without it, we wouldn't know which specific antiderivative to choose.
Example calculation
Let's find ∫√x dx from x=1 to x=4.
First, find the antiderivative: (2/3)x^(3/2) + C
Evaluate at the bounds:
- At x=4: (2/3)(4)^(3/2) = (2/3)(8) = 16/3
- At x=1: (2/3)(1)^(3/2) = (2/3)(1) = 2/3
Subtract the lower bound from the upper bound: (16/3) - (2/3) = 14/3 ≈ 4.6667
Result
The definite integral from 1 to 4 of √x dx is 14/3 or approximately 4.6667.
Common mistakes
- Forgetting the constant of integration (C)
- Incorrectly applying the power rule (adding exponents instead of adding 1)
- Miscounting the exponent when simplifying (3/2 instead of 1/2 + 1)
- Not simplifying the final fraction (leaving it as x^(3/2)/(3/2))
FAQ
What is the difference between definite and indefinite integrals?
An indefinite integral finds all antiderivatives of a function (includes a constant of integration). A definite integral calculates the net area under a curve between two points.
Why do we need the constant of integration?
The constant accounts for the infinite number of functions that could have the same derivative. Without it, we wouldn't know which specific antiderivative to choose.
Can I integrate √x using substitution?
Yes, you can use substitution by letting u = √x, du = (1/2)x^(-1/2) dx, and dx = 2u du. Then ∫√x dx = ∫u * 2u du = 2∫u^2 du = (2/3)u^3 + C = (2/3)x^(3/2) + C.