199+199+199+199*199+199*9/3=?
199+33+199+44+199=?
199+33+199+44+199
=(199x3)+(33+44)
=597+77
=674
k mik nha!^_^
:3)))
Số cần tìm là:
199+33+199+44+199= 674
Đáp số: 674
Tính bằng cách thuận tiện nhất.
199 + 199 + 199 + 199 x 7
=199x3+199x7
=199x(3+7)
=199x10
=1990
hok tốt
= 199 x ( 3 + 7 )
= 199 x 10
= 1990
199 + 199 + 199 + 199 x 7
= 199 x 1 + 199 x 1 + 199 x 1 + 199 x 7
= 199 x ( 1 + 1 + 1 + 7 )
= 199 x 10
= 1990
Hok tốt
Tìm x
\(\frac{x-199}{6}+\frac{x-199}{12}+\frac{x-199}{20}+\frac{x-199}{30}+\frac{x-199}{42}=\frac{5}{14}\)\(\frac{5}{14}\)
Mình lỡ đánh nhầm 2 lần \(\frac{5}{14}\)nha :)) chỉ 1 lần thôi
\(\frac{x-199}{6}+\frac{x-199}{12}+\frac{x-199}{20}+\frac{x-199}{30}+\frac{x-199}{42}=\frac{5}{14}\)
\(\left(x-199\right)\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\right)=\frac{5}{14}\)
\(\left(x-199\right)\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\right)=\frac{5}{14}\)
\(\left(x-199\right)\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{6}-\frac{1}{7}=\frac{5}{14}\right)\)
\(\left(x-199\right)\left(\frac{1}{2}-\frac{1}{7}\right)=\frac{5}{14}\)
\(\left(x-199\right).\frac{5}{14}=\frac{5}{14}\)
\(\Leftrightarrow x-199=1\)
\(\Leftrightarrow x=200\)
a) So sánh A và B, biết:A=199 mũ 199+1/199 mũ 200+1 VÀ B=199 mũ 198+1/199 mũ 199+1
b)chứng minh:3<1+1/2+1/3+1/4+1/5+...+1/63<6
c)Chứng minh A ko thuộc N biết:A=1/2+1/3+1/4+1/5+...+1/50
Bài luyện thi HSG thầy cho khó quá giúp mk vs
17/35 *(3/5 +6/11-9/199)
----------------------------------- = ?
51/70*(1/5+2/11-3/199)
chứng minh 199^3 -199 chia hết cho 200
\(199^3-199=199.\left(199^2-1\right)=199.\left(199+1\right).\left(199-1\right)=199.200.198⋮200\left(đpcm\right)\)
\(199^3-199=199\left(199^2-1\right)=199\left(199+1\right)\left(199-1\right)=199.200.198⋮200\left(đpcm\right)\)
CM rằng 199^3-199 chia hết cho 200
\(199^3-199\\=199(199^2-1)\\=199(199-1)(199+1)\\=199\cdot198\cdot200\)
Vì \(199\cdot198\cdot200⋮200\) nên \(199^3-199⋮200\)
Tính nhanh:
a)11/7 x 8/13 + 8/13 x 3/7 + 8/13
b)5/7 x 8/13 + 8/13 x 9/7 - 8/13
c)156 x 199 - 57 x 199 - 199
a.11/7.8/13+8/13.3/7+8/13
=8/13.(11/7+3/7+1)
=8/13.3
=24/13
b.5/7.8/13+8/13.9/7-8/13
=8/13.(5/7+9/7-1)
=8/13.1
=8/13
c.157.199-56.199-199
=199.(157-56-1)
=199.100
19900
-(2012-199+20)-(-199+20)
-(2012-199+20)-(-199+20)
=-2012+199-20+199-20
=-2012+(200-1)-20+(200-1)-20
=-2012+200+200-1-1-20-20
=-2012+(200+200)-(20+20+1+1)
=-2012+400-42
=-1612-42=-1654