integral from 0 to 2 of (4x^3-3x^2+2x)
Let's integrate: ∫02(4x3 -3x2 + 2x)dx
ⅰ ∫(4x3 -3x2 + 2x)dx = ∫4x3dx -∫3x2dx + ∫2xdx
∫4x3dx -∫3x2dx + ∫2xdx
ⓘ A constant factor stays in front of the integral. An antiderivative of x^n is x^(n+1)/(n+1), for n ≠ -1: ∫4x3dx = 4·x44, -∫3x2dx = -3·x33, ∫2xdx = 2·x22
4·x44 -3·x33 + 2·x22
ⓘ Multiplying a fraction by a number multiplies its numerator: 4·x44 = 4x44, 3·x33 = 3x33, 2·x22 = 2x22■A fraction is simplified by dividing the numerator and the denominator by the same number: 4x44 = x4, -3x33 = -x3, 2x22 = x2
▷ x4 -x3 + x2
Let's evaluate for the interval [0, 2]: (24 -23 + 22) -(04 -03 + 02)
ⓘ Powers are computed before multiplications, additions and subtractions. An integer power is a repeated product: 24 = 2·2·2·2 = 16, 23 = 2·2·2 = 8, 22 = 2·2 = 4■A minus sign before a parenthesis changes the sign of each of its terms: -(04 -03 + 02) = -04 + 03 -02
16 -8 + 4 -04 + 03 -02
ⓘ Start from 16 and move back 8 on the number line: 16 -8 = 8■Adding 0 changes nothing: 4 + 0 + 0 + 0 = 4
8 + 4
ⓘ Start from 8 and move forward 4 on the number line: 8 + 4 = 12
▶Integral:   12