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3x^2-1÷x(x^2+1) solve by partial fraction method |
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Answer» ONG>ANSWER: (x²+3x)/(x²+1)(X+1)²={(x+1)²+(x+1)-2}/(x²+1)(x+1)²=(1/x²+1)+1/(x²+1)(x+1)-2/(x²+1)(x+1)² So we need only break down the kast two TERMS into partial fractions: (i) Let 1/(x²+1)(x+1)=(ax+b)/(x²+1)+c(x+1) 1=(ax+b)(x+1)+c(x²+1) x=-1→ c=½ ■ x=0→1=b+½→ b=½ ■ compare x²-term→0=a+c→ a=-½ ■ (ii) Let 1/(x²+1)(x+1)²=(Ax+B)/(x²+1)+C/(x+1)+D(x+1)² 1=(Ax+B)(x+1)²+C(x+1)(x²+1)+D(x²+1) x=-1→ D=½ ■ x=0→1=B+C+½ B+C=½ x³-terms→0≈A+C→A=-C x-term→0=A+B+C+½→0=B+½→ B=-½ ■→ C=1 ■ A=-C=-1 ■ ∴Required partial fractions : 1/(x²+1)+½(1-x)/(x²+1)+½/(x+1)-2(x+½)/(x²+1)+2/(x+1)-1/(x+1)² =½(1/(x²+1)-(5/2)(x/(x²+1)-1/(x+1)²+½/(x+1) |
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