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y42x=5y^4-2x=5, find d2yd2x\frac{d^2y}{d^2x} at (2,1)(-2,1)

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Q. y42x=5y^4-2x=5, find d2yd2x\frac{d^2y}{d^2x} at (2,1)(-2,1)
  1. Implicit Differentiation: To find the second derivative of yy with respect to xx, we first need to implicitly differentiate the given equation with respect to xx. The given equation is y42x=5y^4 - 2x = 5. Differentiating both sides with respect to xx, we get: 4y3(dydx)2=04y^3 \cdot \left(\frac{dy}{dx}\right) - 2 = 0 Now, we solve for dydx\frac{dy}{dx}: 4y3(dydx)=24y^3 \cdot \left(\frac{dy}{dx}\right) = 2 dydx=24y3\frac{dy}{dx} = \frac{2}{4y^3} dydx=12y3\frac{dy}{dx} = \frac{1}{2y^3}
  2. Solving for dydx\frac{dy}{dx}: Next, we need to differentiate dydx\frac{dy}{dx} with respect to xx again to find the second derivative d2ydx2\frac{d^2y}{dx^2}. This requires using the chain rule since yy is a function of xx.\newlineDifferentiating 12y3\frac{1}{2y^3} with respect to xx, we get:\newlined2ydx2=3(12y4)(dydx)\frac{d^2y}{dx^2} = -3 \cdot \left(\frac{1}{2y^4}\right) \cdot \left(\frac{dy}{dx}\right)
  3. Finding Second Derivative: We already found that (dydx)=12y3(\frac{dy}{dx}) = \frac{1}{2y^3}, so we substitute this into our expression for the second derivative:\newlined2ydx2=3×(12y4)×(12y3)\frac{d^2y}{dx^2} = -3 \times \left(\frac{1}{2y^4}\right) \times \left(\frac{1}{2y^3}\right)\newlined2ydx2=34y7\frac{d^2y}{dx^2} = \frac{-3}{4y^7}
  4. Evaluating at (2,1)(-2,1): Now we need to evaluate the second derivative at the point (2,1)(-2,1). We substitute y=1y = 1 into the expression for the second derivative:\newlined2ydx2=3417\frac{d^2y}{dx^2} = -\frac{3}{4 \cdot 1^7}\newlined2ydx2=34\frac{d^2y}{dx^2} = -\frac{3}{4}

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