Q. If −1−x2+y2=y3−5y then find dxdy at the point (1,−2).Answer: dxdy∣∣(1,−2)=
Implicit Differentiation: First, we need to implicitly differentiate both sides of the equation with respect to x. The equation is −1−x2+y2=y3−5y. Differentiating both sides with respect to x gives us: dxd(−1−x2+y2)=dxd(y3−5y).
Differentiate Left Side: Differentiate the left side of the equation term by term.(d)/(dx)(−1)=0 because the derivative of a constant is 0.(d)/(dx)(−x2)=−2x because the derivative of x2 is 2x, and we multiply by the coefficient −1.(d)/(dx)(y2)=2y(dy/dx) because y is a function of x, so we use the chain rule.The left side becomes 0−2x+2y(dy/dx).
Differentiate Right Side: Differentiate the right side of the equation term by term.dxd(y3)=3y2dxdy because we use the chain rule, where the derivative of y3 is 3y2, and we multiply by dxdy.dxd(−5y)=−5dxdy because the derivative of 5y with respect to x is 5 times the derivative of y with respect to x.The right side becomes y30.
Combine Derivatives: Combine the derivatives to form an equation:−2x+2ydxdy=3y2dxdy−5dxdy.Now we need to solve for dxdy.
Group and Factor: Group all the terms containing dxdy on one side and the remaining terms on the other side:2ydxdy−3y2dxdy+5dxdy=2x.Factor out dxdy from the left side:dxdy(2y−3y2+5)=2x.
Solve for dxdy: Solve for dxdy by dividing both sides by (2y−3y2+5):dxdy=2y−3y2+52x.
Substitute Point: Substitute the point (1,−2) into the equation to find (dy/dx) at that point:$(dy/dx)|_{(\(1\),\(-2\))} = \frac{\(2\)(\(1\))}{\(2\)(\(-2\)) - \(3\)(\(-2\))^\(2\) + \(5\)}.
Calculate \(\frac{dy}{dx}\): Calculate the value of \(\left(\frac{dy}{dx}\right)\) at the point \((1, -2)\): \(\left.\frac{dy}{dx}\right|_{(1,-2)} = \frac{2}{(-4 - 3(4) + 5)}\). \(\left.\frac{dy}{dx}\right|_{(1,-2)} = \frac{2}{(-4 - 12 + 5)}\). \(\left.\frac{dy}{dx}\right|_{(1,-2)} = \frac{2}{(-11)}\). \(\left.\frac{dy}{dx}\right|_{(1,-2)} = -\frac{2}{11}\).
More problems from Find derivatives of using multiple formulae