Q. Let x2−y2=28.What is the value of dx2d2y at the point (8,−6) ?Give an exact number.
Differentiate Once: We are given the equation x2−y2=28. To find dx2d2y, we need to differentiate the equation with respect to x twice.First, let's differentiate the equation once with respect to x.Using the chain rule, the derivative of x2 with respect to x is 2x, and the derivative of y2 with respect to x is 2ydxdy.So, the first derivative of the equation is:dx2d2y0
Solve for dxdy: Now, we need to solve for dxdy. Rearrange the equation to isolate dxdy: 2y(dxdy)=2xdxdy=2y2xdxdy=yx
Differentiate Again: Next, we differentiate the equation again with respect to x to find the second derivative, dx2d2y. Differentiating yx with respect to x using the quotient rule, which is v2v(dxdu)−u(dxdv), where u=x and v=y, we get: dx2d2y=y2y(1)−x(dxdy)
Substitute dxdy: We already found that dxdy=yx, so we substitute this into our expression for the second derivative:dx2d2y=y2y−x(yx)dx2d2y=y2y−yx2
Simplify Expression: Now we simplify the expression:dx2d2y=y3y2−x2Since we know from the original equation that x2−y2=28, we can rewrite y2−x2 as −28.dx2d2y=y3−28
Substitute Point: Finally, we substitute the given point (8,−6) into the expression to find the exact value of the second derivative at that point.dx2d2y=(−6)3−28dx2d2y=−216−28dx2d2y=21628
Final Answer: Simplify the fraction to get the final answer: dx2d2y=7.71
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