SOLUTION: What is the derivative of this function.?If y= x^2 - 4x and x = sqrt of 2t^2 +1 find dy/dt when t = sqrt of 2.

Algebra ->  Functions -> SOLUTION: What is the derivative of this function.?If y= x^2 - 4x and x = sqrt of 2t^2 +1 find dy/dt when t = sqrt of 2.       Log On


   

Question 168880: What is the derivative of this function.?If y= x^2 - 4x and x = sqrt of 2t^2 +1 find dy/dt when t = sqrt of 2.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
By the chain rule,
dy%2Fdt=%28dy%2Fdx%29%2A%28dx%2Fdt%29
dy%2Fdx=2x-4

dy%2Fdt=%28dy%2Fdx%29%2A%28dx%2Fdt%29
dy%2Fdt=%282x-4%29%2A%28%282t%29%2F%28sqrt%282t%5E2%2B1%29%29%29
dy%2Fdt=%282%2Asqrt%282t%5E2%2B1%29-4%29%2A%28%282t%29%2F%28sqrt%282t%5E2%2B1%29%29%29
When t=sqrt%282%29, then
t%5E2=2

dy%2Fdt=%282%2Asqrt%285%29-4%29%2A%28%282%2Asqrt%282%29%29%2F%28sqrt%285%29%29%29
dy%2Fdt=%284%2Asqrt%282%29%28sqrt%285%29-2%29%29%2F%28sqrt%285%29%29