Question

计算题，求完整的解题过程

Answer 1

19.
原式=4-1-3√3+2-√3
=（4-1+2）-（3√3+√3）
=5-4√3

20.
原式=(a-2)/(a+1)(a-1)+a(a-2)/(a-1)² -2/(a+1)
=(a-2)/(a+1)(a-1)-2/(a+1)+a(a-2)/(a-1)²

=[(a-2)-2(a-1)]/(a+1)(a-1)+a(a-2)/(a-1)²
=(-a)/(a+1)(a-1)+a(a-2)/(a-1)²
=(-a)(a-1)/(a+1)(a-1)² +a(a-2)(a+1)/(a+1)(a-1)²

=-a[a-1-(a-2)(a+1)]/(a+1)(a-1)²
=-a (a-1-a²+a+2)/(a+1)(a-1)²
=-a(-a²+2a+1)/(a+1)(a-1)²
=-√2(-2+2√2+1)/(2-1)(√2-1)
=-√2(2√2-1)/(√2-1)
=（√2 -4）/(√2-1)
=(√2-4)(√2+1)
=2-3√2-4
=-3√2-2

Answer 2

Answer 3

Answer 4