計算2×(1/2+1/3 +1/4 +1/5 )+4×(1/3 +1/4 +1/5 )+6×(1/4 +1/5 )+8×1/5 之值為何?
(A)13
(B)12
(C)11
(D)10
答案:登入後查看
統計: A(29), B(76), C(79), D(1238), E(0) #364739
統計: A(29), B(76), C(79), D(1238), E(0) #364739
詳解 (共 3 筆)
#619998
令w=1/2, x=1/3, y=1/4, z=1/5
=> 2w+2x+2y+2z
+ 4x+4y+4z
+ 6y+6z
+ 8z
---------------------------
2w+6x+12y+20z=1+2+3+4=10
28
2
#785644
展開後,能約成1的就約成1,剩下的分母一樣慢慢加就好...
5
0