=6.3/2.5 +6.3/5.8+...+6.3/203.206
=6(3/2.5+3/5.8+...+3/203.206)
=6(1/2-1/5+1/5-1/8+...+1/203-1/206)
=6[(1/2-1/206)+(1/5-1/5)+(1/8-1/8)+...+(1/203-1/203)]
=6(1/2-1/206)=6(103/206-1/206)=6. 102/206=6. 51/103=306/103
A=6.( 3/2.5+3/5.8+...+3/203.206)
=6.(1/2-1/5+1/3-1/8+...+1/202-1/206)
=6.(1/2-1/206)=306/103
A = \(\frac{18}{2.5}+\frac{18}{5.8}+...+\frac{18}{203.206}\)
= \(18.\left(\frac{1}{2.5}+\frac{1}{5.8}+...+\frac{1}{203.206}\right)\)
= \(\frac{18}{3}.\left(\frac{3}{2.5}+\frac{3}{5.8}+...+\frac{3}{203.206}\right)\)
= \(6.\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{203}-\frac{1}{206}\right)\)
= \(6.\left(\frac{1}{2}-\frac{1}{206}\right)\)
= \(6.\frac{51}{103}\)
= \(2\frac{100}{103}\)
\(2\frac{100}{103}\)với \(\frac{306}{103}\)giống nhau chứ sao nữa hả bn!
