Homework Help Forum: calculus

Posted by Fran on Thursday, October 29, 2009 at 6:59pm.

If 5x^2+3x+xy=2 andy=-12, find y'(2) by implicit differentiation.

• calculus - Reiny, Thursday, October 29, 2009 at 7:23pm

  I get 10x + 3 + x(dy/dx) + y = 0 dy/dx = -(10x + 3 +y)/x so when y = -12 your original equation becomes 5x^2 - 9x - 2 = 0 (5x+1)(x-2) = 0 x = -1/5 or x = 2 so we want dy/dx when x=2 and y = -12 plug those values in and you got it.

  
  

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