Optimization

AP Calculus AB· difficulty 3/5

The largest rectangle inscribed under the parabola y=4x2y = 4 - x^2, base on the xx-axis, has area

  • A

    88

  • B

    833\tfrac{8\sqrt 3}{3}

  • C

    1639\tfrac{16\sqrt 3}{9}

  • D

    3239\tfrac{32\sqrt 3}{9}

    check_circle

Explanation

A(x)=2x(4x2)A(x) = 2x(4 - x^2). A=86x2=0x=2/3A' = 8 - 6x^2 = 0 \Rightarrow x = 2/\sqrt 3. A=2(2/3)(44/3)=(4/3)(8/3)=32/(33)=323/9A = 2(2/\sqrt 3)(4 - 4/3) = (4/\sqrt 3)(8/3) = 32/(3\sqrt 3) = 32\sqrt 3/9.

Want 10 more like this — adaptive to your weak spots?

Related questions