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If 
y(x)=(x^(x^(x))),x > 0 then 
(d^(2)x)/(dy^(2))+20 at 
x=1 is equal to:

If y(x)=\left(x^{x^{x}}\right), x>0 then d2xdy2+20 \frac{d^{2} x}{d y^{2}}+20 at x=1 x=1 is equal to:

Full solution

Q. If y(x)=(xxx),x>0 y(x)=\left(x^{x^{x}}\right), x>0 then d2xdy2+20 \frac{d^{2} x}{d y^{2}}+20 at x=1 x=1 is equal to:
  1. Find First Derivative: First, we need to find the first derivative of yy with respect to xx. To do this, we will use the chain rule and the property that the derivative of xxx^x is xx(1+ln(x))x^x(1+\ln(x)).\newlineLet's denote u=xxu = x^x, so y=xuy = x^u. Then we have:\newlinedydx=ddx(xu)=uxu1+ln(x)xududx\frac{dy}{dx} = \frac{d}{dx}(x^u) = u \cdot x^{u-1} + \ln(x) \cdot x^u \cdot \frac{du}{dx}\newlineSince u=xxu = x^x, we can also find dudx\frac{du}{dx} using the same property:\newlinedudx=xx(1+ln(x))\frac{du}{dx} = x^x(1+\ln(x))\newlineNow we substitute dudx\frac{du}{dx} back into the expression for xx11.
  2. Substitute dudx\frac{du}{dx}: Substituting dudx\frac{du}{dx} into the expression for dydx\frac{dy}{dx}, we get:\newlinedydx=uxu1+ln(x)xuxx(1+ln(x))\frac{dy}{dx} = u \cdot x^{u-1} + \ln(x) \cdot x^u \cdot x^x(1+\ln(x))\newlineSimplifying, we have:\newlinedydx=xxxxx1+ln(x)xxxxx(1+ln(x))\frac{dy}{dx} = x^x \cdot x^{x^x-1} + \ln(x) \cdot x^{x^x} \cdot x^x(1+\ln(x))
  3. Find Second Derivative: Now we need to find the second derivative of yy with respect to xx, which is d2ydx2\frac{d^2y}{dx^2}. This involves differentiating the expression for dydx\frac{dy}{dx} once more with respect to xx. However, this is a very complex expression, and differentiating it directly is not straightforward. Instead, we will use the implicit differentiation technique by taking the natural logarithm of both sides of the original equation y=xxxy = x^{x^x} and then differentiating.\newlineLet's take the natural logarithm of both sides:\newlineln(y)=ln(xxx)\ln(y) = \ln(x^{x^x})\newlineUsing the property of logarithms, we get:\newlineln(y)=xxln(x)\ln(y) = x^x \cdot \ln(x)\newlineNow we differentiate both sides with respect to xx.
  4. Take Natural Logarithm: Differentiating both sides with respect to xx, we get:\newlineddx(ln(y))=ddx(xxln(x))\frac{d}{dx}(\ln(y)) = \frac{d}{dx}(x^x \cdot \ln(x))\newlineUsing the chain rule on the left side, we have:\newline(1y)dydx=xxln(x)+xx(1+ln(x))(\frac{1}{y}) \cdot \frac{dy}{dx} = x^x \cdot \ln(x) + x^x \cdot (1+\ln(x))\newlineNow we need to isolate dydx\frac{dy}{dx} and then differentiate again to find d2ydx2\frac{d^2y}{dx^2}.
  5. Differentiate with Chain Rule: Multiplying both sides by yy to isolate dydx\frac{dy}{dx}, we get: dydx=y(xxln(x)+xx(1+ln(x)))\frac{dy}{dx} = y \cdot (x^x \cdot \ln(x) + x^x \cdot (1+\ln(x))) Now we need to differentiate this expression with respect to xx to find d2ydx2\frac{d^2y}{dx^2}. However, this is where a mistake was made. The differentiation of the right side with respect to xx is incorrect. The correct differentiation should take into account the product rule and the chain rule for the term xxln(x)x^x \cdot \ln(x), which was not applied correctly.

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