so sánh:\(A=\frac{8^{18}+1}{8^{19+1}}vaB=\frac{8^{23}+1}{8^{24+1}}\)
So Sánh
a) 8^18 + 1/8^19 +1 và 8^23 + 1/8^24 +1
Áp dụng tính chất \(\frac{a}{b}< 1\Rightarrow\frac{a}{b}< \frac{a+m}{b+m}\left(m\in N\right)\)
Ta có: \(\frac{8^{23}+1}{8^{24}+1}< \frac{8^{23}+1-1+8^5}{8^{24}+1-1+8^5}=\frac{8^{23}+8^5}{8^{24}+8^5}=\frac{8^5.\left(8^{18}+1\right)}{8^5.\left(8^{19}+1\right)}=\frac{8^{18}+1}{8^{19}+1}\)
Vậy \(\frac{8^{23}+1}{8^{24}+1}< \frac{8^{18}+1}{8^{19}+1}\)
Tham khảo lời giải tại link : https://olm.vn/hoi-dap/detail/90330086488.html
Bài 1 : So sánh A với B
a, \(A=\frac{8^{18}+1}{8^{19}+1}\)\(B=\frac{8^{23}+1}{8^{24}+1}\)
b, \(A=\frac{5^5}{5+5^2+5^3+5^4}\)
\(B=\frac{3^5}{3+3^2+3^3+3^4}\)
ta có A= \(\frac{8^{18}+1}{8^{19} +1}\)=> 8A=\(\frac{8^{19}+8}{8^{19}+1}\)= \(\frac{\left(8^{19}+1\right)+7}{8^{19}+1}\)=\(\frac{8^{19}+1}{8^{19} +1}\)+\(\frac{7}{8^{19}+1}\) =1+\(\frac{7}{8^{19}+1}\) =\(\frac{7}{8^{19}+1}\)
B= \(\frac{8^{23}+1}{8^{24}+1}\)=> 8B=\(\frac{8^{24}+8}{8^{24}+1}\)= \(\frac{\left(8^{24}+1\right)+7}{8^{24}+1}\)=\(\frac{8^{24}+1}{8^{24}+1}\)+\(\frac{7}{8^{24}+1}\) =1+\(\frac{7}{8^{24} +1}\)=\(\frac{7}{8^{24}+1}\)
vì \(8^{19}\)<\(8^{24}\)=> \(8^{19}\)+1 >\(8^{24}\)+1 => \(\frac{7}{8^{19}+1}\)<\(\frac{7}{8^{24}+1}\)=> A<B
a) ta có \(8A=\frac{8^{19}+8}{8^{19}+1}=1+\frac{7}{8^{19}+1}\\ 8B=\frac{8^{24}+8}{8^{24}+1}=1+\frac{7}{8^{24}+1}\)
Vì \(8^{24}+1>8^{19}+1\\\frac{7}{8^{24}+1}< \frac{7}{8^{19}+1} \)
vậy 8A>8B nên A>B
nhầm dấu
\(8^{19}\) +1<\(8^{24}\)+1=> \(\frac{7}{8^{19}+1}\)<\(\frac{7}{8^{24}+1}\)=> A<B
so sánh 8^18+1/8^19+1 và 8^23 +1 /8^24+1
mn giúp mik vs mik đang v=cần gấp
so sánh 8^18+1/8^19+1 và 8^23 +1 /8^24+1
mn giúp mik vs mik đang v=cần gấp
\(A=\frac{8^{18}+1}{8^{19}+1}\) VÀ \(B=\frac{8^{23}+1}{8^{23}+4}\)
\(A=\frac{8^{18}+1}{8^{^{19}}+1}vàB=\frac{8^{^{25}}+1}{8^{^{24}}+1}.sosánh\)
bạn kiểm tra lại B xem sao
A=\(\frac{8^{18^{ }}+1}{8^{19}+1}\)=> 8A=8.
Xin lỗi nha mình chưa làm xong
So sánh A và B
a) A = 224 ; B = 316.
b) A = ( 0,1 )15 ; B = ( 0,3 )30.
c) A = \(\left(\frac{-1}{4}\right)^8\) ; B = \(\left(\frac{1}{8}\right)^5\).
d) A = 1027 ; B = 913.
e) A = \(\frac{8^{18}+1}{8^{19}+1}\); B = \(\frac{8^{23}+1}{8^{24}+1}\).
f) A = \(\frac{5^5}{5+5^2+5^3+5^4}\); B = \(\frac{3^5}{3+3^2+3^3+3^4}\).
Ai làm nhanh và đúng nhất mik sẽ tik cho 3 cái 3 hôm >_<
a) \(A=2^{24}=\left(2^3\right)^8=8^8.\)(1)
\(B=3^{16}=\left(3^2\right)^8=9^8\)(2)
Từ (1) và (2) \(\Rightarrow A< B\)
Vậy \(A< B.\)
b) \(B=\left(0,3\right)^{30}=\left(0,3^2\right)^{15}=0,09^{15}\)(1)
\(A=\left(0,1\right)^{15}\)(2)
Từ (1) và (2) \(\Rightarrow A>B\)
Vậy \(A>B.\)
c) \(A=\left(\frac{-1}{4}\right)^8=\left(\frac{1}{4}\right)^8=\left[\left(\frac{1}{2}\right)^2\right]^8=\left(\frac{1}{2}\right)^{16}\)(1)
\(B=\left(\frac{1}{8}\right)^5=\left[\left(\frac{1}{2}\right)^3\right]^5=\left(\frac{1}{2}\right)^{15}\)(2)
Từ (1) và (2) \(\Rightarrow A>B\)
Vậy \(A>B.\)
d) \(A=102^7=102^6.102\)(1)
\(B=9^{13}=9^{12}.9=\left(9^2\right)^6.9=81^6.9\)(2)'
Từ (1) và (2) \(\Rightarrow A>B\)
Vậy \(A>B.\)
e) \(8A=8\frac{8^{18}+1}{8^{19}+1}=\frac{8^{19}+8}{8^{19}+1}=1+\frac{7}{8^{19}+1}\)(1)
\(8B=8\frac{8^{23}+1}{8^{24+1}}=\frac{8^{24}+8}{8^{24}+1}=1+\frac{7}{8^{24}+1}\)(2)
Từ (1) và (2) \(\Rightarrow8A>8B\Rightarrow A>B\)
Vậy \(A>B.\)
f) \(A=\frac{5^5}{5+5^2+5^3+5^4}=\frac{5^4}{1+5+5^2+5^3}=\frac{625}{156}>\frac{468}{156}=3.\)(1)
\(B=\frac{3^5}{3+3^2+3^3+3^4}=\frac{3^4}{1+3+3^2+3^3}=\frac{81}{40}< \frac{120}{40}=3.\)(2)
Từ (1) và (2) \(\Rightarrow A>B\)
Vậy \(A>B.\)
a, ta có A=2^24=64^4
B=3^16=81^4
Vì 64^4<81^4
Vậy 2^24<3^36
b, ta có A=0,1^15
B=0,3^30=0,09^15
Vì 0,1^15< 0,09^15
Vậy 0,1^15<0,3^30
so sánh\(A=\frac{31}{13}-\left(\frac{7}{32}+\frac{8}{2}\right)vaB=\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}-\frac{28}{41}\right)\)
\(\frac{18}{37}+\frac{8}{24}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)
(( MN ƠI GIÚP MIK nha ))
(( MIK ĐANG CẦN LẮM ))
18/37 + 8/24 + 19/37 - 1/23/24 + 2/3
= 18/37 + 19/37 + 1/3 + 2/3 - 1/23/24
= 1 + 1 - 1/23/24
= 2 - 1/23/24
= 1/24
( chú ý : 1/3 là rút gọn của 8/24 )
\(\frac{18}{37}+\frac{8}{24}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)
\(=\frac{18}{37}+\frac{1}{3}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)
\(=\left(\frac{18}{37}+\frac{19}{37}\right)+\left(\frac{1}{3}+\frac{2}{3}\right)-1\frac{23}{24}\)
\(=1+1-1\frac{23}{24}\)
\(=2-1\frac{23}{24}=\frac{1}{24}\)
\(\frac{18}{27}+\frac{8}{24}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)
\(=\frac{18}{27}+\frac{8}{24}+\frac{19}{37}-\frac{47}{24}+\frac{16}{24}\)
\(=\left(\frac{18}{37}+\frac{19}{37}\right)+\left(\frac{8}{24}+\frac{16}{24}\right)-\frac{47}{24}\)
\(=\frac{37}{37}+\frac{24}{24}-\frac{47}{24}\)
\(=1+1-\frac{47}{24}\)
\(=2-\frac{47}{24}\)
\(=\frac{48}{24}-\frac{47}{24}\)
\(=\frac{1}{24}\)