Kaplan SAT Subject Math Level 1-Practice 1

Kaplan SAT Subject Test Mathematics Level 1 : 2015-2016

Call number: Y510.76 SAT 2015/2016

注意raw score 不是做对题的数目，要减去错的题数 ×0.25。

Errors: Q18, 35, 42, 46, 49. 做对45道题，做错5道题

45 － 5×0.25 = 44,     分数730。

Can we have better explanation for selecting C answer?

i = (-1)½      i24 = ((-1)1/2)24  = (-1)12= ((-1)2)6= 1

                (-i)24 = (-1 * i)24  = (-1)24 *(i)24 = i24 

Thus, i24  + (-i)24 = 2

               i26 = ((-1)1/2)26  = (-1)13=  -1

                (-i)26 = (-1 * i)26  = (-1)26 *(i)26 = i26 

          i26  + (-i)26 = -2

        (-i)23 = (-1 * i)23  = (-1)23 *(i)23 = -i23 

     (-i)25 = (-1 * i)25  = (-1)25 *(i)25 = -i25 

     (-i)27 = (-1 * i)27  = (-1)27 *(i)27 = -i27 

 i23  + (-i)23 = i25  + (-i)25 = i27  + (-i)27 = 0

只有三种选择   in  + (-i)n is 2 (n is multiple of 4), -2 (n is multiple of 2 not 4), 0 (n is odd number)

 I was able to draw the picture. But I am not so sure about my drawing. I think the radis is  r2 = 62 +  52. Thus, I can't figure out the answer. 

note squr should be sqrt