Calculus Examples
∫xx2+1dx , u=x2+1
Step 1
Step 1.1
Let u=x2+1. Find dudx.
Step 1.1.1
Differentiate x2+1.
ddx[x2+1]
Step 1.1.2
By the Sum Rule, the derivative of x2+1 with respect to x is ddx[x2]+ddx[1].
ddx[x2]+ddx[1]
Step 1.1.3
Differentiate using the Power Rule which states that ddx[xn] is nxn-1 where n=2.
2x+ddx[1]
Step 1.1.4
Since 1 is constant with respect to x, the derivative of 1 with respect to x is 0.
2x+0
Step 1.1.5
Add 2x and 0.
2x
2x
Step 1.2
Rewrite the problem using u and du.
∫12udu
∫12udu
Step 2
Since 12 is constant with respect to u, move 12 out of the integral.
12∫1udu
Step 3
The integral of 1u with respect to u is ln(|u|).
12(ln(|u|)+C)
Step 4
Simplify.
12ln(|u|)+C
Step 5
Replace all occurrences of u with x2+1.
12ln(|x2+1|)+C