Find the area of the curve y = 4x³ between the end points x = [-2, 3]

Concept:

The area of the curve y = f(x) is given by:

A = \(\rm \int_{x_1}^{x_2}f(x) dx\)

where x1 and x2 are the endpoints between which the area is required.

Imp. Note: The net area will be the addition of the area below the x-axis and the area above the x-axis.

Calculation:

The f(x) = y = 4x³

Given the end points x1 = -2, x2 = 3

Area of the curve (A) = \(\rm \left|\int_{-2}^3 4x^3dx\right|\)

⇒ A = \(\rm \left|\int_{-2}^0 4x^3dx\right| + \left|\int_0^3 4x^3dx\right|\)

⇒ A = \(\rm \left|4\left[x^4\over4\right]_{-2}^0\right| + \left|4\left[x^4\over4\right]_0^3\right|\)

⇒ A = \(\rm \left|\left[0- 2^4\right]\right| + \left|\left[3^4 - 0\right]\right| \)

⇒ A = \(\rm \left|-16\right| + \left|81\right|\)

⇒ A = 97

Additional Information

Integral property:

• ∫ xn dx = \(\rm x^{n+1}\over n+1\)+ C ; n ≠ -1
• \(\rm∫ {1\over x} dx = \ln x\) + C
• ∫ ex dx = ex+ C
• ∫ ax dx = (ax/ln a) + C ; a > 0,  a ≠ 1
• ∫ sin x dx = - cos x + C
• ∫ cos x dx = sin x + C