6.1 Areas Between Curves/19: Difference between revisions
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[[File:6.1.19 graph actual.png|right|350px|]] | |||
19) | 19) | ||
<math>\ | <math> | ||
\begin{align} | |||
& \color{red} \mathbf{x=4+y^2} | |||
& \color{royalblue}\mathbf{x=2y^2} \\ | |||
\end{align} | |||
</math> | |||
<math> | |||
\begin{align} | |||
4+y^2 &= 2y^2 \\ | |||
4 &=y^2 \\ | |||
y &=\sqrt{4} \\ | |||
y &= \pm2 \\[2ex] | |||
\int_{-2}^{2} [(4+y^2)-(2y^2)]dy \\ | |||
=\int_{-2}^{2} [4-y^2]dy \\[2ex] | |||
=\left[4y-\frac{y^3}{3}\right]\Bigg|_{-2}^{2}\\[2ex] | |||
=4(2)-\frac{(2)^3}{3}-(4(-2)-\frac{(-2)^3}{3})\\[2ex] | |||
=8-\frac{8}{3}-(-8+\frac{8}{3})\\[2ex] | |||
=16-\frac{16}{3}\\[2ex] | |||
=\frac{48}{3}-\frac{16}{3}\\[2ex] | |||
=\frac{32}{3}\\ | |||
\end{align} | |||
</math> | |||