Set f(x) = 0 and solve for x:
75 - 3x² = 0
3x² = 75
x² = 25
x = ±5
Since we are looking at the interval [0, 8], we only consider x = 5. The graph crosses the x-axis at x = 5, which is within the given interval.
Since the graph crosses the x-axis at x = 5, we need two integrals to represent the area: one from 0 to 5, and another from 5 to 8. The function is positive from 0 to 5, and negative from 5 to 8. To calculate the area, we must take the absolute value of the integral from 5 to 8.
∫₀⁵ (75 - 3x²) dx + ∫₅⁸ |75 - 3x²| dx
To avoid the absolute value, we can rewrite the second integral as:
∫₀⁵ (75 - 3x²) dx - ∫₅⁸ (75 - 3x²) dx
∫₀⁵ (75 - 3x²) dx = [75x - x³]₀⁵ = (75(5) - 5³) - (0) = 375 - 125 = 250
∫₅⁸ (75 - 3x²) dx = [75x - x³]₅⁸ = (75(8) - 8³) - (75(5) - 5³) = (600 - 512) - (375 - 125) = 88 - 250 = -162