15/25....4/5
Bài 1.2: Tính nhanh:
5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5
25 + 25 + 25 + 25 + 25 + 25 +25 + 25
45 + 45 + 45 + 45 + 15 + 15 + 15 + 15
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18
125 + 125 + 125 + 125 - 25 - 25 - 25 - 25
5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5=5x10=50
25 + 25 + 25 + 25 + 25 + 25 +25 + 25=25x8=200
45 + 45 + 45 + 45 + 15 + 15 + 15 + 15=(45x4)+(15x4)=180+60=240
5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5
= 5 x 10
= 50
25 + 25 + 25 + 25 + 25 + 25 +25 + 25
= 25 x 8
= 200
45 + 45 + 45 + 45 + 15 + 15 + 15 + 15
= 45 x 4 + 15 x 4
= 180 + 60
= 240
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18
= (2 + 18) + (4 + 16) + (8 + 12) + (6 + 14) + 10
= 20 + 20 + 20 + 20 + 10
= 20 x 4 + 10
= 80 + 10
= 90
125 + 125 + 125 + 125 - 25 - 25 - 25 - 25
= 4 x (125 - 25)
= 4 x 100
= 400
(Tick cho mk pls ^^)
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
tính nhanh:a) 15/14-(17/13-87+5/4)+(17/23-15/14+1/4) b) 1/25-4/27+(-23/27+-1/25-5/43)+5/43-4/7
2 ^ 15 : 2 ^ 13 + 3 ^ 2. 2 ^ 3 - 5 ^ 2 - 2 ^ 0
81 . ( 27 + 9 ^ 15) : (3 ^ 5 + 3 ^ 32)
(4 ^ 42 .123 - 23 . 4 ^ 42) : (4 ^ 15 . 4 ^ 27)
(15 . 3 ^ 7 - 3 ^ 8) : (4 . 9 ^ 4)
(100 . 5 ^ 7 + 5 ^ 11 : 25 ) : ( 5 . 5 ^ 13 : 25 ^ 2)
( 2 ^ 5 . 3 ^ 6 . 5 ^ 7 + 2 ^ 6 . 3 ^ 7 . 5 ^ 8 ) : ( 2 ^ 4 . 3 ^ 5 . 5 ^ 6)
(4 ^ 5 . 10 . 5 ^ 6 + 2 ^ 8 . 25 ^ 5) : ( 2 ^ 8 . 5 ^ 4 + 5 ^ 4 + 5 ^ 7 . 2 ^ 5)
tặng 2 like cho người giải !!!
1) -145.(13 - 57) + 57.(10 -145)
2) 17.(15 - 16) + 16.( 17- 20)
3) -38.(25 - 4) + 25.(-4 + 38 )
4) 23.(145 - 17) - 145.(23 - 6)
5) 24.(15 - 4) + 4.(24 - 15)
6) 199.(15 - 17) - 199.(-17 + 5)
7) -39.(5 - 99) + 99.(10 - 39)
1: \(=-145\cdot13+145\cdot57+57\cdot10-57\cdot145=-1315\)
2: \(=17\cdot15-17\cdot16+16\cdot17-16\cdot20=255-320=-65\)
3: \(=-38\cdot25+38\cdot4-25\cdot4+25\cdot38=13\cdot4=52\)
4: \(=23\cdot145-23\cdot17-145\cdot23+145\cdot6=479\)
5: \(=24\cdot15-24\cdot4+4\cdot24-4\cdot15=360-60=300\)
6: \(=199\left(15-17+17-5\right)=199\cdot10=1990\)
7: \(=-39\cdot5+39\cdot99+99\cdot10-99\cdot39=795\)
1: =−145⋅13+145⋅57+57⋅10−57⋅145=−1315=−145⋅13+145⋅57+57⋅10−57⋅145=−1315
2: =17⋅15−17⋅16+16⋅17−16⋅20=255−320=−65=17⋅15−17⋅16+16⋅17−16⋅20=255−320=−65
3: =−38⋅25+38⋅4−25⋅4+25⋅38=13⋅4=52=−38⋅25+38⋅4−25⋅4+25⋅38=13⋅4=52
4: =23⋅145−23⋅17−145⋅23+145⋅6=479=23⋅145−23⋅17−145⋅23+145⋅6=479
5: =24⋅15−24⋅4+4⋅24−4⋅15=360−60=300=24⋅15−24⋅4+4⋅24−4⋅15=360−60=300
6: =199(15−17+17−5)=199⋅10=1990=199(15−17+17−5)=199⋅10=1990
7: =−39⋅5+39⋅99+99⋅10−99⋅39=795
Tính hợp lí
1) -145.(13 - 57) + 57.(10 -145)
2) 17.(15 - 16) + 16.( 17- 20)
3) -38.(25 - 4) + 25.(-4 + 38 )
4) 23.(145 - 17) - 145.(23 - 6)
5) 24.(15 - 4) + 4.(24 - 15)
6) 199.(15 - 17) - 199.(-17 + 5)
7) -39.(5 - 99) + 99.(10 - 39)
11/15 + 8/15= Tính phân số
6/7 - 5/21=
25/4 x 16/100
7 x 2/49 =
4/3 : 2/9
5/8 : 25 =
11/15 + 8/5= Tính phân số
6/7 - 5/21=
25/4 x 16/100
7 x 2/49 =
4/3 : 2/9
5/8 : 25 =
bài 1. Tính
a) 7/-25 + -8/25 b) 6/13 + -15/39 c) 5/7 + 4/-14 d) -8/18 + -15/27
bài 2. Tính
a) 3/5 + -7/4 b) (-2) + -5/8 c) 1/8 + -5/9 d) 6/13 + -14/39 e) -18/24 + 15/21
`@` `\text {Ans}`
`\downarrow`
`1,`
`a)`
`-7/25 + (-8)/25`
`= (-7 - 8)/25`
`= -15/25`
`= -3/5`
`b)`
`6/13 + (-15)/39`
`= 18/39 + (-15)/39`
`= (18 - 15)/39`
`= 3/39`
`= 1/13`
`c)`
`5/7 + 4/(-14)`
`= 10/14 + (-4)/14`
`= (10 - 4)/14`
`= 6/14`
`= 3/7`
`d)`
`-8/18 + (-15)/27`
`= -4/9 + (-5)/9`
`= (-4-5)/9`
`= -9/9 = -1`
`2,`
`a)`
`3/5 + (-7)/4`
`= 12/20 + (-35)/20`
`= (12 - 35)/20`
`=-23/20`
`b)`
`(-2) + (-5)/8`
`= (-16)/8 + (-5)/8`
`= (-16 - 5)/8`
`= -21/8`
`c)`
`1/8 + (-5)/9`
`= 9/72 + (-40)/72`
`= (9-40)/72`
`= -31/72`
`d)`
`6/13 + (-14)/39`
`= 18/39 + (-14)/39`
`= (18 - 14)/39`
`= 4/39`
`e)`
`(-18)/24 + 15/21`
`= (-3)/4 + 5/7`
`= (-21)/28 + 20/28`
`= (-21 + 20)/28`
`= -1/28`
tính bằng cách thuận tiện nhất 4/25×1/3+4/15×13/5-1/15×4×4/5
a/ 5 .\(\sqrt{0,01}\) - \(\sqrt{0,25}\)
b/ 15\(\dfrac{1}{4}\) : (-\(\dfrac{5}{7}\)) - 25\(\dfrac{1}{4}\) : (-\(\dfrac{5}{7}\))
c/ \(\dfrac{5^4\cdot20^4}{25^4\cdot4^5}\)
a, =2.0,1-0,5 b,=\(\left(15\dfrac{1}{4}-25\dfrac{1}{4}\right):\left(-\dfrac{5}{7}\right)\)
=0,2-0,5 = -10:(\(\dfrac{-5}{7}\))
=-0,3 = 14
c, \(=\dfrac{5^4.\left(4.5\right)^4}{\left(5^2\right)^4.4^5}=\dfrac{5^4.4^4.5^4}{5^8.4^5}=\dfrac{1}{4^{ }}\)