integral from 0.75 to 0.9 of 3x^2

解答

\int_{0.75}^{0.9} 3 x^{2} d x

0.307125

求解步骤

\int_{0.75}^{0.9} 3 x^{2} d x

提出常数:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= 3 \cdot \int_{0.75}^{0.9} x^{2} d x

使用幂法则

= 3 [\frac{x ^{3}}{3}]_{0.75}^{0.9}

化简

= 3 [0.33333 \dots x^{3}]_{0.75}^{0.9}

带入上下限计算后得:

0.102375

= 3 \cdot 0.102375

化简

= 0.307125

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