Question

芋泥(⁠◍⁠•⁠ᴗ⁠•⁠◍⁠)⁠

求解兩題！！

例題 18
(1+1&s)x(1+2*x)x(1+ss) xx(1+9s95)x(1+x56) =?
93
解:原式
危ㄨㄨ>
X
43x9541
93x95
9
2x4

3
例題 20
1
解:
23-7124
1
Iv2x3x4
+
1×2×3×4'2×3×4×5
+
1
3×4×5×6
+
+
1
7x8x9x 10
=?

Answer 1

✨ ベストアンサー ✨

kevin_maphy

18.
原式=((2*2)/(1*3))*((3*3)/(2*4))*((4*4)/(3*5))*...*((94*94)/(93*95))*((95*95)/(94*96))
分子分母對消後=(2/1)*(95/96)=95/48

20.
原式=(1/3)((1/(1*2*3))-(1/(2*3*4)))+(1/3)((1/(2*3*4))-(1/(3*4*5)))+(1/3)((1/(3*4*5))-(1/(4*5*6)))+...+(1/3)((1/(7*8*9))-(1/(8*9*10)))
前後項對消後=(1/3)*(1/(1*2*3)-1/(8*9*10))=119/2160

芋泥(⁠◍⁠•⁠ᴗ⁠•⁠◍⁠)⁠

謝謝🥰🥰