Question

求这三道题的详细做法！！！主要是前两题，第三题不会就算了。急急急！！！我一会要交作业了ԅ

求这三道题的详细做法！！！主要是前两题，第三题不会就算了。急急急！！！我一会要交作业了😱

Answer 1

Answer 2

1 化简，设3√a = x， 3√b = y
则原式 =[ (x^3 + x^2 y)/(y^3 + x y^2) - 1] / (x-y) - 1/y
= [ (x^3 + x^2 y - y^3 - x y^2)/(y^3 + x y^2) ] / (x-y) - 1/y
= {[ (x-y)(x^2+xy+y^2) + x y (x- y)]/(y^3 + x y^2) }/ (x-y) - 1/y
= [ (x-y)(x^2+xy+y^2 + xy) /y^2(y + x ) ]/ (x-y) - 1/y
= (x+y)/y^2 - y/y^2
= x/y^2 = 3√2/3√4^2 = 1/2

2 另x^1/2 = a, a+1/a =3

原式 =[ a^3 +(1/a)^3 - (a+1/a)] / (a^2 -2 + a^-2)
= [( a+1/a)(a^2 -1 + 1/a ^2) - (a+1/a)]/(a^2 -2 + a^-2)
= [( a+1/a)(a^2 -1 + 1/a ^2 -1) ]/(a^2 -2 + a^-2)
= a+1/a = 3

Answer 3

追答

以上是第一题第二题
下面是第三题

Answer 4

追问

求第一题～

追答

图是歪的，拍张正的，看不清啊

Answer 5

追答