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\(A=1+5+5^2+5^3+..+5^{100}\)
\(5A=5+5^2+5^3+..+5^{101}\)
\(A=\frac{5^{101}-1}{4}\)\(SUYRA\) \(A< B\)
\(A=5^0+5+5^2+...+5^{100}.\)
\(\Rightarrow5A=5+5^2+5^3+...+5^{101}\)
\(\Rightarrow5A-A=4A=\left(5+5^2+5^3+...+5^{101}\right)-\left(5^0+5+5^2+...+5^{100}\right)\)
\(=5^{101}-1\)
\(\Rightarrow A=\frac{5^{101}-1}{4}\)
Còn lại tự lm nha bn
Áp dụng a/b > 1 => a/b > a+m/b+m (a,b,m thuộc N*)
=> \(\frac{5^{100}+6}{5^{100}+4}>\frac{5^{100}+6+1}{5^{100}+4+1}\)
\(>\frac{5^{100}+7}{5^{100}+5}\)
A=5^100+6=5^100+5+1=5^101+1 ; 5^100+4=5^100+5-1=5^101-1
B=5^100+7=5^100+5+2=5^101+2 ; 5^100+5=5^101
vs nha
Ta có:
\(\frac{1}{2}< \frac{2}{3}\)
\(\frac{3}{4}< \frac{4}{5}\)
\(\frac{5}{6}< \frac{6}{7}\)
\(...\)
\(\frac{99}{100}< \frac{100}{101}\)
\(\Rightarrow\frac{1}{2}.\frac{3}{4}.\frac{5}{6}...\frac{99}{100}< \frac{2}{3}.\frac{4}{5}.\frac{6}{7}...\frac{100}{101}\)
\(\Rightarrow M< N\)
A = 1*2*3 + 2*3*4 + 3*4*5 ... + 99*100*101
=> 4A = 1*2*3*4 + 2*3*4*4 + 3*4*5*4 + ... +99*100*101*4
=> 4A = 1*2*3*4 + 2*3*4*(5 - 1) + 3*4*5*( 6 - 2) + ... + 99*100*101*(102 - 98)
=> 4A = 1*2*3*4 + 2*3*4*5 - 1*2*3*4 + 3*4*5*6 - 2*3*4*5 + ... + 99*100*101*102 - 98*99*100*101
=> 4A = 99*100*101*102
=> 4A = 101989800
=> A = 25497450
2.(1+2+3+4+.....+100).(89.2)
2.5050.89.2
2(5050.89)
=898900
(1+1+2+2+3+3+4+4+5+5+6+6+...+100+100)* (89 *2 )
=(1+100)+(1+100)+(2+99)+...+(54+57)+(55+56)+(55+56)*187
=101+101+101+...+101+101+101*187
=101*100*187
=10100*187=1888700
\(A=\dfrac{100^{100}-1}{100^{100}-5}=\dfrac{\left(100^{100}-1\right)\left(100^{100}+1\right)}{\left(100^{100}-5\right)\left(100^{100}+1\right)}=\dfrac{100^{200}-1}{\left(100^{100}-5\right)\left(100^{100}+1\right)}\)
\(B=\dfrac{100^{100}+5}{100^{100}+1}=\dfrac{\left(100^{100}+5\right)\left(100^{100}-5\right)}{\left(100^{100}-5\right)\left(100^{100}+1\right)}=\dfrac{100^{200}-25}{\left(100^{100}-5\right)\left(100^{100}+1\right)}\)
\(\Rightarrow A>B\)
B=\(\frac{5^{100}+7}{5^{100}+5}\)=\(\frac{5^{100}+6+1}{5^{100}+4+1}\)
Mà \(\frac{5^{100}+6+1}{5^{100}+4+1}\)>\(\frac{5^{100}+6}{5^{100}+4}\)
\(\Rightarrow\)B>A