a,
ĐKXĐ: 2x - 2 \(\ne\)0 <=> 2x \(\ne\)2 <=> x \(\ne\)1
2 - 2x2 \(\ne\)0 <=> 2( 1 - x2) \(\ne\)0 <=> (1 - x)(1 + x) \(\ne\)0
<=> x \(\ne\)-1
b,
C = \(\dfrac{x}{2x-2}+\dfrac{x^2+1}{2-2x^2}\)
= \(\dfrac{x}{2x-2}-\dfrac{x^2+1}{2\left(x^2-1\right)}\)
= \(\dfrac{x}{2\left(x-1\right)}-\dfrac{x^2+1}{2\left(x+1\right)\left(x-1\right)}\)
= \(\dfrac{x\left(x+1\right)-x^2-1}{2\left(x-1\right)\left(x+1\right)}\)
= \(\dfrac{x^2+x-x^2-1}{2\left(x-1\right)\left(x+1\right)}\)
= \(\dfrac{x-1}{2\left(x-1\right)\left(x+1\right)}\)
= \(\dfrac{1}{2\left(x+1\right)}\)
c,
Để C = \(-\dfrac{1}{2}\)
<=> \(\dfrac{1}{2\left(x+1\right)}=\dfrac{-1}{2}\)
<=> \(\dfrac{1}{x+1}=-1\)
<=> x + 1 = -1
<=> x = -2
d,
Để C > 0
<=> \(\dfrac{1}{2\left(x+1\right)}\)> 0
<=> 2(x + 1) > 0
<=> x + 1 > 0
<=> x > -1