Moi nguoi tra loi thu cau hoi nay nhe ( de thoi ma )
Cho S= 3/1*4+3/4*7+3/7*10+....+3/40*43+3/43*46
Hay chung to rang S < 1
32/60 + 2/3 :3 +1/2 -1/4
Moi nguoi tra loi ho minh nhe
1/2 + 7/3 +9/2 -1/3 +4/9 - 1 va 5/9
Moi nguoi tra loi ho minh nhe
Minh hoi 2 cau nhe
Chung to rang : (9m+9)(9m+2)(9m+3)(9m+4) chia het cho 5 voi moi m thuoc N
Ai tra loi cau hoi nay toi co 10 nick GIUP TOI GIAI TOAN se vao tung nick de an like cho nguoi --do
- Ai tra loi truoc duoc 3 like
-xong nhi duoc 2 like
-Ai tra loi chinh xac duoc 5 like
GIAI THICH luon nhe cac ban
-nhung nguoi con lai toi cho 1like
cho s =3/1*4+3/4*7+3/7*10+......+3/43*46.chung minh rang s <1
\(\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+...+\frac{3}{43\cdot46}=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{43}-\frac{1}{46}=1-\frac{1}{46}< 1\)
\(\left(\frac{3}{a\cdot\left(a+3\right)}=\frac{a+3-3}{a\cdot\left(a+3\right)}=\frac{1}{a}-\frac{1}{a+3}\right)\)
\(S=\frac{3}{1\times4}+\frac{3}{4\times7}+...+\frac{3}{43\times46}\)
\(3S=3-\frac{3}{4}+\frac{3}{4}-\frac{3}{7}+...+\frac{3}{43}-\frac{3}{46}\)
\(3S=3-\frac{3}{46}\)
\(3S=\frac{135}{46}\)
\(S=\frac{45}{46}< 1\)
Vậy ra có điều phải chứng minh
\(S=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{43.46}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{43}-\frac{1}{46}\)
\(=1-\frac{1}{46}< 1\)
Vậy S < 1 (đpcm)
?Mot doi xe cho hang , 3 o to di dau moi xe cho duoc 3,5 tan va 4 o to sau moi xe cho duoc 2,8 tan . Hoi trung binh moi xe o to cho duoc bao nhieu tan hang
nhanh thi duoc ma nhanh len trong 10 put nua ma ko tra loi thi thoi
giai ra nhe
cau giai ra nhe
mình rất vui khi được làm quen với bạn
3 ô tô đầu chở được số tấn hàng là :
3,5 * 4 =14 ( tấn )
4 ô tô đi sau chở được số tấn hàng là :
2.8 * 4 = 11,2 ( tấn )
Trung bình mỗi xe ô tô chở được số tấn hàng là :
( 14 + 11,2 ) : 7 = 3,6 ( tấn )
Đáp số : 3,6 tấn hàng
cac ban oi giai gium minh bai nay nhe neu ai giai duoc minh cho 1 like luon ok
chung minh rang :
10 mu n cong voi 5 mu 3 chia het cho 9
43 mu 43 tru cho 17 mu 17 chia het cho 10
nhanh nhe minh muon chu nhat la co cau tra loi cang som cang tot nhe
Cho S = 3/1*4+3/4*7+3/7*10+...+3/40*43+3/43+46. Hãy chứng tỏ S < 1
\(S=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{40.43}+\frac{3}{43.46}\) < 1
\(S=3\left(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{40.43}+\frac{1}{43.46}\right)\)
\(S=3.\frac{1}{3}\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}\right)\)
\(\Rightarrow S=1-\frac{1}{46}\Rightarrow S< 1\left(đpcm\right)\)
\(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{40.43}+\frac{3}{43.46}\)
= \(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}\)
= \(1-\frac{1}{46}< 1\)
\(\Rightarrow S< 1\left(đpcm\right)\)
neu co ba o vuong, o thu 1 co 3 so nhu sau: 2, -1, -3. O thu 2 co 3 so: 5, -4, 3, va o cuoi cung cung co 3 so: -5, 6, 9. Vay nguoi ta hoi lam the nao de cho tong cua ba hop duoc bang nhau, nhung cac ban chi duoc di chuyen mot so cua o nay qua o khac thoi nhe, nho day. Ban nao tra loi duoc cho mik ket ban nhe!
Cho S = \(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7\cdot10}+....+\frac{3}{40\cdot43}+\frac{3}{43\cdot46}\) . Hay chung to rang S < 1
\(S=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{43}-\frac{1}{46}\)
\(s=1-\frac{1}{46}< 1\)
Vậy S<1
\(S=\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+...+\frac{3}{43\cdot46}\)
\(S=1\left[\frac{1}{1\cdot4}+\frac{1}{4\cdot7}+\frac{1}{7\cdot10}+...+\frac{1}{43\cdot46}\right]\)
\(S=1\left[1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{43}-\frac{1}{46}\right]\)
\(S=1\left[1-\frac{1}{46}\right]=1\cdot\frac{45}{46}=\frac{45}{46}< 1(đpcm)\)
S = \(\frac{1}{1}-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}\)
S = \(\frac{1}{1}-\frac{1}{46}\)
S = \(\frac{46}{46}-\frac{1}{46}\)
S = \(\frac{45}{46}< 1\)
Hay S < 1
Vậy S < 1 (đpcm)
3/4*1+3/4*7+3/7*10+........+3/40*43+3/43*46 chứng mính s<1
Ta có: \(\frac{3}{1.4}+\frac{3}{4.7}+......+\frac{3}{40.43}+\frac{3}{43.46}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+....+\frac{1}{40}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}\)
\(=1-\frac{1}{46}\)
Vì \(\frac{1}{46}>0\Rightarrow1-\frac{1}{46}< 1\)
Vậy \(\frac{3}{1.4}+\frac{3}{4.7}+....+\frac{3}{43.46}< 1\)