Tinh :1/2+2/6+3/9+4/12+5/15+6/18
Tinh :1/2+2/6+3/9+4/12+5/15+6/18
ta thấy 2/6=1/3,3/9=1/3,4/12=1/3,6/18=1/3,5/15=1/3
1/2+1/3+1/3+1/3+1/3+1/3=13/6
Đáp số :13/6
tinh nhanh
1+2+3+4+5+6+7+8+9+11+12+13+14+15+16+17+18+19
1+2+3+4+5+6+7+8+9+11+12+13+14+15+16+17+18+19
=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)
=20+20+20+20+20+20+20+20+20
=20x9
=180
\(1+2+3+4+5+6+7+8+9+11+12+13+14+15+16+17+18+19\)
\(=\left(1+19\right)+\left(2+18\right)+\left(3+17\right)+\left(4+16\right)+\left(5+15\right)+\left(6+14\right)+\left(7+13\right)+\left(8+12\right)+\left(9+11\right)\)\(=20+20+20+20+20+20+20+20+20\)
\(=20\times9\)
\(=180\)
1+2+3+4+5+6+7+8+9+11+12+13+14+15+16+17+18+19
=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)
=20+20+20+20+20+20+20+20+20
=20x9
=180
Tính nhanh:A=1*5*6+2*10*12+3*15*18+4*20*24+5*25*30/1*3*5+2*6*10+3*9*15+4*12*20+5*15*25
ta có : (ghi lại đề)
=6+12+18+24+30/3+6+9+12+15
=2*(3/3+6/6+9/9+12/12+15/15)
=2*(1+1+1+1+1)
=2*5=10
chúc main học tốt nhé
bài 3: Tính:
1) 1/6 - -5/6 2) 6/13 - -14/39 3) 4/5 - 4/-18 4) 7/21 - 9/-36
5) -12/18 - -21/35 6) -3/21 - 6/42 7) -18/24 - 15/21 8) 1/6 - 2/5
các bn giup mik mik vs
1)1/6 - - 5/6 = 1/6 + 5/6 = 1
2)6/13 - -14/39 = 6/13 + 14/39= 32/39
3)4/5 - 4/-18 = 4/5 + 4/18= 46/45
4)7/21 - 9/-36 = 7/21 + 9/36 = 7/12
5)-12/18 - -21/35 = -12/18 + 21/35 = -1/15
6)-3/21 - 6/42 = -2/7
7)-18/24 - 15/21 = -41/28
8)1/6 - 2/5 =-7/30
tim cac tich bang nhau ma khong can tinh ket qua cua moi tich :
15 . 2 . 6 ; 4 . 4 . 9; 5 . 3 . 12 ; 8 . 18 ; 15 . 3 . 4 ; 8 . 2 . 9
Các tích bằng nhau là:
15.2.6 = 5.3.12 = 15.3.4
4.4.9 = 8.18 = 8.2.9
Ủng hộ mk nha ^_-
Sau đây là cách giải của mình :
Các tích bằng nhau là :
15.2.6 = 5.3.12 = 15.3.4
4.4.9 = 8.18 = 8.2.9
Xong rồi k mk nhoa !
15.2.6 = 5.3.12 = 15.3.4
4.4.9 = 9.18 = 9.2.9
ai k mik mik sẽ k lại @@@@@@@
tính : a) 2/3 *( 2/18+6/12-3/33 ) b) 6/14+4/25-5/10*3/16 c)5/25*(9/18+16/32-12/46) + 9/17 d)11/32:(14/18-16/27) + (2/3-5/15) e) ( 1/9+2/17)+3/6-(12/17-1/2) +5/9
bài 1:
1/4 + 2/3 2/7 + 2/3 2/5 + 1/3 2/3 + 1/2 1/3 + 3/5 4/5 + 1/3
1/8 + 3/4 1/36 + 5/12 1/3 + 1/6 + 1/18.
bài 2:
15/16 - 3/16 17/18 - 5/6 3/4 - 4/9 1/2 - 2/5 5/6 - 3/10 3-1/3
4/5 - 1/10 5/2 - 1 5/8 - 2/5.
Bài 1 Tính nhanh
a) -3/7 + 5/13 + 3/7
b) -5/21+-2/21+8/24
c) -5/11+(-6/11+2)
d) (-1/32+1/2)+15/32
e)5/17+ -6/13 + 3/4 + 7/-13+12/17
f) 7/23+-18/18+-4/9+16/23+-5/8
g)1/3+-3/4+3/5+-1/36+1/15+-2/9
h)-1/2+1/3+-1/4+-2/8+4/18+4/9
a)\(-\dfrac{3}{7}+\dfrac{5}{13}+\dfrac{3}{7}\)
=\(\left(-\dfrac{3}{7}+\dfrac{3}{7}\right)+\dfrac{5}{13}\)
=\(0+\dfrac{5}{13}\)
=\(\dfrac{5}{13}\)
a ) - 8 / 24 + - 4 / 12
b ) - 20 / 35 + 16 / 24
c ) - 3 / 9 + - 6 / 15
d ) 3 / 13 - 4 / 10
e ) 5 / 17 - 9 / 15
g ) 9 / 18 - 6 / 15 + 3 / - 9
h ) 5 / 4 - 1 / 2 + - 7 / 8
câu a :
\(\dfrac{-8}{24}+\dfrac{-4}{12}=\dfrac{-1}{3}+\dfrac{-1}{3}=\dfrac{-2}{3}\)
câu b :
\(\dfrac{-20}{35}+\dfrac{16}{24}=\dfrac{-4}{7}+\dfrac{2}{3}=\dfrac{2}{21}\)
câu c :
\(\dfrac{-3}{9}+\dfrac{-6}{15}=\dfrac{-1}{3}+\dfrac{-2}{5}=\dfrac{-11}{15}\)
câu d :
\(\dfrac{3}{13}-\dfrac{4}{10}=\dfrac{3}{13}-\dfrac{2}{5}=\dfrac{-11}{65}\)
câu e :
\(\dfrac{5}{17}-\dfrac{9}{15}=\dfrac{5}{17}-\dfrac{3}{5}=\dfrac{-26}{85}\)
câu g :
\(\dfrac{9}{18}-\dfrac{6}{15}+\dfrac{3}{-9}=\dfrac{9}{18}-\dfrac{6}{15}+\dfrac{-3}{9}\\ =\dfrac{1}{2}-\dfrac{2}{5}+\dfrac{-1}{3}=\dfrac{-7}{30}\)
câu h :
\(\dfrac{5}{4}-\dfrac{1}{2}+\dfrac{-7}{8}=\dfrac{10}{8}-\dfrac{4}{8}+\dfrac{-7}{8}=\dfrac{-1}{8}\)