The problem consists of three parts: a. Evaluate two logarithmic expressions: $\log_{\frac{1}{2}}4$ and $\log_{0.1}10$. b. Find the square roots of the complex number $3-4i$. c. Express two rational functions in partial fractions: $\frac{x}{(x+3)(x+2)}$ and $\frac{2x^2+6x+1}{x(x+1)}$.

AlgebraLogarithmsComplex NumbersSquare RootsPartial Fractions
2025/5/3

1. Problem Description

The problem consists of three parts:
a. Evaluate two logarithmic expressions: log124\log_{\frac{1}{2}}4 and log0.110\log_{0.1}10.
b. Find the square roots of the complex number 34i3-4i.
c. Express two rational functions in partial fractions: x(x+3)(x+2)\frac{x}{(x+3)(x+2)} and 2x2+6x+1x(x+1)\frac{2x^2+6x+1}{x(x+1)}.

2. Solution Steps

a.
i. Evaluate log124\log_{\frac{1}{2}}4. Let y=log124y = \log_{\frac{1}{2}}4. Then, (12)y=4(\frac{1}{2})^y = 4. Since 4=224 = 2^2 and 12=21\frac{1}{2} = 2^{-1}, we have (21)y=22(2^{-1})^y = 2^2, which means 2y=222^{-y} = 2^2. Therefore, y=2-y = 2, so y=2y = -2.
ii. Evaluate log0.110\log_{0.1}10. Let y=log0.110y = \log_{0.1}10. Then (0.1)y=10(0.1)^y = 10. Since 0.1=110=1010.1 = \frac{1}{10} = 10^{-1}, we have (101)y=10(10^{-1})^y = 10, which means 10y=10110^{-y} = 10^1. Therefore, y=1-y = 1, so y=1y = -1.
b. Find the square roots of 34i3-4i. Let 34i=a+bi\sqrt{3-4i} = a+bi, where aa and bb are real numbers. Squaring both sides, we get 34i=(a+bi)2=a2+2abib2=(a2b2)+2abi3-4i = (a+bi)^2 = a^2 + 2abi - b^2 = (a^2 - b^2) + 2abi.
Equating the real and imaginary parts, we have:
a2b2=3a^2 - b^2 = 3 and 2ab=42ab = -4, which implies ab=2ab = -2, so b=2ab = -\frac{2}{a}.
Substituting bb into the first equation:
a2(2a)2=3a^2 - (-\frac{2}{a})^2 = 3
a24a2=3a^2 - \frac{4}{a^2} = 3
a44=3a2a^4 - 4 = 3a^2
a43a24=0a^4 - 3a^2 - 4 = 0
Let u=a2u = a^2. Then u23u4=0u^2 - 3u - 4 = 0.
(u4)(u+1)=0(u-4)(u+1) = 0.
So u=4u = 4 or u=1u = -1. Since aa is real, a2a^2 must be non-negative. Therefore, a2=4a^2 = 4, which means a=2a = 2 or a=2a = -2.
If a=2a = 2, then b=22=1b = -\frac{2}{2} = -1.
If a=2a = -2, then b=22=1b = -\frac{2}{-2} = 1.
Therefore, the square roots are 2i2-i and 2+i-2+i.
c.
i. Express x(x+3)(x+2)\frac{x}{(x+3)(x+2)} in partial fractions.
We can write x(x+3)(x+2)=Ax+3+Bx+2\frac{x}{(x+3)(x+2)} = \frac{A}{x+3} + \frac{B}{x+2}.
Multiplying both sides by (x+3)(x+2)(x+3)(x+2), we get x=A(x+2)+B(x+3)x = A(x+2) + B(x+3).
If x=3x = -3, then 3=A(3+2)+B(3+3)=A-3 = A(-3+2) + B(-3+3) = -A, so A=3A = 3.
If x=2x = -2, then 2=A(2+2)+B(2+3)=B-2 = A(-2+2) + B(-2+3) = B, so B=2B = -2.
Therefore, x(x+3)(x+2)=3x+32x+2\frac{x}{(x+3)(x+2)} = \frac{3}{x+3} - \frac{2}{x+2}.
ii. Express 2x2+6x+1x(x+1)\frac{2x^2+6x+1}{x(x+1)} in partial fractions.
Since the degree of the numerator is equal to the degree of the denominator, we perform polynomial long division first.
2x2+6x+1x(x+1)=2x2+6x+1x2+x=2+4x+1x(x+1)\frac{2x^2+6x+1}{x(x+1)} = \frac{2x^2+6x+1}{x^2+x} = 2 + \frac{4x+1}{x(x+1)}.
Now we express 4x+1x(x+1)\frac{4x+1}{x(x+1)} in partial fractions.
4x+1x(x+1)=Cx+Dx+1\frac{4x+1}{x(x+1)} = \frac{C}{x} + \frac{D}{x+1}.
Multiplying both sides by x(x+1)x(x+1), we get 4x+1=C(x+1)+Dx4x+1 = C(x+1) + Dx.
If x=0x = 0, then 1=C(0+1)+D(0)=C1 = C(0+1) + D(0) = C, so C=1C = 1.
If x=1x = -1, then 4+1=C(1+1)+D(1)=D-4+1 = C(-1+1) + D(-1) = -D, so 3=D-3 = -D, which means D=3D = 3.
Therefore, 4x+1x(x+1)=1x+3x+1\frac{4x+1}{x(x+1)} = \frac{1}{x} + \frac{3}{x+1}.
So, 2x2+6x+1x(x+1)=2+1x+3x+1\frac{2x^2+6x+1}{x(x+1)} = 2 + \frac{1}{x} + \frac{3}{x+1}.

3. Final Answer

a.
i. log124=2\log_{\frac{1}{2}}4 = -2
ii. log0.110=1\log_{0.1}10 = -1
b. The square roots of 34i3-4i are 2i2-i and 2+i-2+i.
c.
i. x(x+3)(x+2)=3x+32x+2\frac{x}{(x+3)(x+2)} = \frac{3}{x+3} - \frac{2}{x+2}
ii. 2x2+6x+1x(x+1)=2+1x+3x+1\frac{2x^2+6x+1}{x(x+1)} = 2 + \frac{1}{x} + \frac{3}{x+1}

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