A = 4/5.7 + 4/7.9 +... +4/15.17
=> 1/2.A = 2/5.7 + 2/7.9 +...+ 2/15.17
= 1/5 - 1/7 + 1/7 - 1/9 +...+1/15 - 1/17
= 1/5 - 1/17
= 17/85 - 5/85
=12/85
=> A = 12/85 : 1/2 = 12/85 . 2 = 24/85
-4/15 - 4/35 - 4/63 - 4/99 - 4/143
Tính hợp lí : \(B=\frac{4}{35}+\frac{4}{63}+\frac{4}{99}+\frac{4}{143}+\frac{4}{195}\)
[1/15+1/35+1/63+1/99].x=4
So sánh A và B biết:
\(A=\frac{21^{19}.27^3+15.4^9.9^4}{6^9.2^{10}+12^{10}};B=\frac{4}{35}+\frac{4}{63}+\frac{4}{99}+\frac{4}{143}+\frac{4}{195}\)
A = \(\frac{2^{19}.27^3+15.4^9.9^4}{6^9.2^{10}+12^{10}}\)va B = \(\frac{4}{35}+\frac{4}{63}+\frac{4}{99}+\frac{4}{143}+\frac{4}{195}\)
So sánh
1/3 - 2/5 +3/35 - 4/63 + 5/99 - 6/143
B = 1/4 + 1/15 + 1/35 + 1/63 + 1/99 + 1/143 + 1/195
Bài 1 :So sánh
A= 2^19 .27^3+15.4^9.9^4/6^9.2^10+12^10 va B = 4/35+4/63+4/99+4/143+4/195
Bài 2 : tìm x biết :
60%.x+0,4.x +x:3=2
So sánh
a) (-2)^300 va (-3)^200
b) A= 2^19 .27^3 +15.4^9 .9^4
6^9 .2^10 +12^10
và B= 4/ 35 + 4 /63 +4/99 +4/143+ 1/195
