2-(2a+b/a+b)÷4a²+4ab+b²/a²-b²=2-(2a+b/a+b)÷(2a+b)²/(a+b)(a-b)=2-(2a+b/a+b)×(a+b)(a-b)/(2a+b)²=2-(a-b/2a+b)代入原式=2-(-1-1/2)/(-2+1/2)=2-1=1