Implicit Differentiation

AP Calculus AB· difficulty 3/5

For xy+y2=8xy + y^2 = 8, find yy' at (1,2)(1, 2).

  • A

    25-\tfrac{2}{5}

    check_circle
  • B

    25\tfrac{2}{5}

  • C

    2-2

  • D

    15-\tfrac{1}{5}

Explanation

y+xy+2yy=0y(x+2y)=yy(1,2)=2/(1+4)=2/5y + xy' + 2y y' = 0 \Rightarrow y'(x + 2y) = -y \Rightarrow y'(1, 2) = -2/(1+4) = -2/5.

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

Related questions