SAT数学题求讲解1.Onacertainnumberline,if-7isadistanceof4fromnand7isadistanceof18fromn,thenn=A25B11C3D-3E-112.Ify=a/a+bandx=a/b,whatisyintermsofxA-1/xB1+xC1+1/xD1/1+xEx/1+x答案两题都

Question

SAT数学题求讲解
1.On a certain number line,if -7 is a distance of 4 from n and 7 is a distance of 18 from n,then n =
A 25 B 11 C 3 D -3 E -11
2.If y = a/a+b and x = a/b,what is y in terms of x
A - 1/x B 1+x C 1 + 1/x D 1/1+x E x/1+x
答案两题都是E，求讲解

Answer 1

第一题,若-7到n这点的距离是4,并且7到n这点的距离是18,那么n等于多少?
答案很显然吧,是-7-4=-11
第二题,1/y=1+b/a
所以1/y=1+1/x
即y=x/(1+x)