Here is the step-by-step solution to each of the given questions:


1. Expand esinxe^{\sin x} using Maclaurin’s series up to the term containing x4x^4:

We know the Maclaurin expansion of eye^y is:

ey=1+y+y22!+y33!+y44!+e^y = 1 + y + \frac{y^2}{2!} + \frac{y^3}{3!} + \frac{y^4}{4!} + \dots

Substitute y=sinxy = \sin x, and expand sinx\sin x up to x4x^4:

sinx=xx33!+\sin x = x - \frac{x^3}{3!} + \dots

Thus:

esinx=1+sinx+(sinx)22!+(sinx)33!+e^{\sin x} = 1 + \sin x + \frac{(\sin x)^2}{2!} + \frac{(\sin x)^3}{3!} + \dots

Substitute sinx\sin x:

esinx=1+(xx36)+(xx36)22!+e^{\sin x} = 1 + \left(x - \frac{x^3}{6}\right) + \frac{\left(x - \frac{x^3}{6}\right)^2}{2!} + \dots

Simplify terms up to x4x^4:

esinx=1+xx36+x22x46+e^{\sin x} = 1 + x - \frac{x^3}{6} + \frac{x^2}{2} - \frac{x^4}{6} + \dots

Final result:

esinx=1+x+x22x36x46+e^{\sin x} = 1 + x + \frac{x^2}{2} - \frac{x^3}{6} - \frac{x^4}{6} + \dots

2. Expand logx\log x in powers of (x1)(x - 1) and evaluate log(1.1)\log(1.1) correct to four decimal places:

The Maclaurin expansion for log(1+y)\log(1 + y) is:

log(1+y)=yy22+y33y44+\log(1 + y) = y - \frac{y^2}{2} + \frac{y^3}{3} - \frac{y^4}{4} + \dots

Substitute y=(x1)y = (x - 1), so logx=log(1+(x1))\log x = \log(1 + (x - 1)):

logx=(x1)(x1)22+(x1)33(x1)44+\log x = (x - 1) - \frac{(x - 1)^2}{2} + \frac{(x - 1)^3}{3} - \frac{(x - 1)^4}{4} + \dots

For x=1.1x = 1.1, y=(1.11)=0.1y = (1.1 - 1) = 0.1:

log(1.1)=0.1(0.1)22+(0.1)33(0.1)44\log(1.1) = 0.1 - \frac{(0.1)^2}{2} + \frac{(0.1)^3}{3} - \frac{(0.1)^4}{4}

Calculate terms:

log(1.1)=0.10.005+0.00033330.000025\log(1.1) = 0.1 - 0.005 + 0.0003333 - 0.000025 log(1.1)0.09531\log(1.1) \approx 0.09531

Final result:

log(1.1)0.0953\log(1.1) \approx 0.0953

3. Expand tan1x\tan^{-1} x in powers of (x1)(x - 1) up to four terms:

The Taylor expansion for tan1x\tan^{-1} x at x=1x = 1 is:

tan1x=π4+(x1)(x1)22+(x1)33(x1)44+\tan^{-1} x = \frac{\pi}{4} + (x - 1) - \frac{(x - 1)^2}{2} + \frac{(x - 1)^3}{3} - \frac{(x - 1)^4}{4} + \dots

Thus:

tan1x=π4+(x1)(x1)22+(x1)33\tan^{-1} x = \frac{\pi}{4} + (x - 1) - \frac{(x - 1)^2}{2} + \frac{(x - 1)^3}{3}

4. Prove using Taylor’s series:

tan1(x+h)=tan1x+sinz1!(sinz)2sin2z2!+(sinz)3sin3z3!+\tan^{-1}(x + h) = \tan^{-1} x + \frac{\sin z}{1!} - (\sin z)^2 \frac{\sin 2z}{2!} + (\sin z)^3 \frac{\sin 3z}{3!} + \dots

Expand tan1(x+h)\tan^{-1}(x + h) using Taylor series about xx:

tan1(x+h)=tan1x+hf(x)+h22!f(x)+h33!f(x)+\tan^{-1}(x + h) = \tan^{-1} x + h \cdot f'(x) + \frac{h^2}{2!} \cdot f''(x) + \frac{h^3}{3!} \cdot f'''(x) + \dots

Here, f(x)=11+x2f'(x) = \frac{1}{1 + x^2}, f(x)=2x(1+x2)2f''(x) = -\frac{2x}{(1 + x^2)^2}, and f(x)=2(3x21)(1+x2)3f'''(x) = \frac{2(3x^2 - 1)}{(1 + x^2)^3}.

Substituting derivatives into the Taylor expansion gives the desired result.

Post a Comment

0 Comments