Đáp án+Giải thích các bước giải:
`a)A=(x/(x+2)+1) : (1- (3x^2)/(4-x^2))` `(ĐKXĐ: x\ne±2;x\ne ±1)`
`=(x+x+2)/(x+2) : (4-x^2-3x^2)/(4-x^2)`
`=(2x+2)/(x+2) : (4-4x^2)/(4-x^2)`
`=(2x+2)/(x+2) : [(2-2x)(2+2x)]/[(2-x)(2+x)]`
`=(2x+2)/(x+2) * [(2-x)(2+x)]/[(2-2x)(2+2x)]`
`= (2-x)/(2-2x)`
`b)B=((2a^2)/(b^2)-1/2) . (1/(2a-b)-1/(2a+b))` `(ĐKXĐ: a\ne ± 2b;a\ne0)`
`=((4a^2)/(2b^2)-(b^2)/(2b^2)) . (2a+b-(2a-b))/[(2a-b)(2a+b)]`
`=(4a^2-b^2)/(2b^2) * (2a+b-2a-b)/[(2a-b)(2a+b)]`
`=(4a^2-b^2)/(2b^2) * (2b)/(4a^2-b^2)`
`=1/b`
