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Tangent line to a sum of transcendental functions

Let y=ex+arctan⁡(x)y = e^x + \arctan(x). Find the equation of the tangent line to this curve at x=0x = 0.

Hint

Differentiate using ddx[ex]=ex\frac{d}{dx}[e^x] = e^x and ddx[arctan⁡x]=11+x2\frac{d}{dx}[\arctan x] = \frac{1}{1+x^2}, then evaluate the function and its derivative at x=0x=0 to build the tangent line y=f(0)+f′(0)(x−0)y = f(0) + f'(0)(x-0).

Step-by-step solution

First find the derivative: y′=ex+11+x2y' = e^x + \frac{1}{1+x^2}, since ddx[ex]=ex\frac{d}{dx}[e^x] = e^x and ddx[arctan⁡x]=11+x2\frac{d}{dx}[\arctan x] = \frac{1}{1+x^2}. Evaluate the slope at x=0x=0: y′(0)=e0+11+02=1+1=2y'(0) = e^0 + \frac{1}{1+0^2} = 1 + 1 = 2.

Next find the point on the curve at x=0x=0: y(0)=e0+arctan⁡(0)=1+0=1y(0) = e^0 + \arctan(0) = 1 + 0 = 1, so the point is (0,1)(0,1). Using the point-slope form y−1=2(x−0)y - 1 = 2(x - 0), the tangent line is y=2x+1y = 2x + 1.

Slope value at the point of tangency

Hint
Step-by-step solution

The slope was found by evaluating the derivative at x equals zero. Since y prime equals e to the x plus one over one plus x squared, plugging in zero gives one plus one, which equals two. So the answer is two.

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