\(\dfrac{10}{50}+\dfrac{-45}{50}+\dfrac{-14}{50}=\dfrac{-49}{50}\)
\(\dfrac{1}{5}+\dfrac{-9}{10}+\dfrac{-7}{25}=\dfrac{-9}{10}+\dfrac{-2}{25}=\dfrac{-49}{50}\)
1.chứng minh
a,S1=1+21+22+23+....+239 chia hết cho 15
b,S2=1257_259 chia hết cho 124
2,Chứng minh
a,A=10n+18n-1 chia hết cho 27
b
1,Tim tap hop cac so x \(\varepsilon\)Z,biet
a.-5/7+1+30/-7_<x_< -1/6+1/3+5/6
b.8/17+5/17<x/17,6/17+9/17
c.-6/7+3/35<x<-2/5+3/7
Tính tổng
a/-1+3-5+7_....+97-99
b/1+2-3-4+...+97+98-99-100
a)4/9. (-9)/4-509:-10/9
b)99/25-(22/5+1/2).25
c)2x-1/4=1/2
d)25%-9/2x-5/2.4^2=5,25
x/3=7/25+ -1/5
4/9 + x/5 =5/11
-5/9 + x/10=1/3
help
x/3=7/25+ -1/5
4/9 + x/5 =5/11
-5/9 + x/10=1/3
Chứng tỏ rằng: 817_ 279_913 chia hết cho 45
Tính 1) 4/5 +13/18 2) 3/7 -11/8 3) -7/10 - -4/5 4) 3/20 -1/25 5) 2/3 - 5/6 6) 1/4 + -3/8 - 19/10 7) -9/10 - -7/18 8) 3/10 - 11/18 9) 3/5 -5/6 + -7/12 10) -4/9 - (-5 )/6 - 3/8
5) 6x – 5 = 3 + 4x 6) x – (17 – x) = x – 7
7) 9 – 25 = (7 – x) – ( 25 + 7) 8) 10 – 2.(4 – 3x) = - 4
9) (-12)2
.x = 56 + 10. 13x 10) 2x2
– 1 = 49
