Tìm x:
249 - (x + 34) = 111
tính nhanh 249 x (17 -111) - 17 x (333 -51)
= 249 x 17 - 249 x 111 - 51 x 111 + 17 x 51
= 17 x (249+51) - 111.(249+51)
= 17 x 300 - 111 x 300
= 300 x (17-111)
= 300 x (-94)
= -28200
Tk mk nha
Tìm x, biết
a) x : − 2 1 15 + 3 1 2 = − 3 4 b) − 5 8 − x : 3 5 6 + 7 3 4 = − 2
c) x − 3 4 − 1 4 = 0 d) 3 4 : 2 4 9 − − 3 x + 2 2 3 = 3 4
e) x − 1 3 = 2 − 3 x f) 3 5 7 x − 1 5 7 x − 1 3 = 2 3
g) − 3 4 3 x − 1 = − 27 64 h) 4 5 2 x + 5 = 256 625
i) x − 2 15 3 = 8 125 k) x + 3 5 x + 3 2 = 64 27
m) x − 1 x + 5 = 6 7 n) 4 13 . 6 5 + 4 13 . 2 5 . 2 x + 1 2 = 10 13
-9 + 111 : x = -12 - 34
Vậy x=?
-9 + 111 :x = -12 - 34
-9 + 111 : x = -46
111 : x = ( -46 ) - ( -9 )
111 : x = -37
x = 111 : ( -37)
x = -3
-9 + 111 : x = -12 - 34
-9 + 111 : x = -46
111 : x = (-46) - (-9)
111 : x = -37
x = 111 : ( -37 )
x = -3
-9+111:x=-12-34
-9 + 111:x = -12 - 34
-9 + 111x = -46
111x = -46 + 9
111x = -37
x = \(-\frac{37}{111}=-\frac{1}{3}\)
Tính nhẩm :
( 1999 + 313 ) – 1999 ; ( 1435 + 213 ) -132034 – ( 34 + 1560 ) ; 1972 – ( 368 + 972 )364 – ( 364 – 111 ) ; 249 – ( 75 – 51 )Giải :
( 1999 + 313 ) – 1999 = 1999 – 1999 + 313 = 313( 1435 + 213 ) – 13 = 1435 + ( 213 – 13 ) = 1435 + 200 = 1635
2034 – ( 34 + 1560 ) = ( 2034 – 34 ) – 1560 = 2000 – 1560 = 4401972 – ( 364 + 972 ) = 1972 – 972 – 368 = 1000 – 368 = 632
c. 364 – ( 364 – 111 ) = 364 – 364 + 111 = 111
249 – ( 75-51 ) = ( 249 + 51 ) – 75 = 300 – 75 = 225
tính nhanh
37 x 46 + 37 x 51 + 111
172 x 47 + 86 x8 - 34 x4
35 x 215 - 35 x 210 -175
48 x 56 + 28 x104
\(37\times46+37\times51+111\)
\(=37\times46+37\times51+37\times3\)
\(=37\times\left(46+51+3\right)\)
\(=37\times100\)
\(=3700\)
------------
\(172\times47+86\times8-34\times4\)
\(=172\times47+172\times4-34\times4\)
\(=172\times\left(47+4\right)-34\times4\)
\(=172\times51-34\times4\)
\(=172\times3\times17-17\times2\times4\)
\(=17\times\left(172\times3-2\times4\right)\)
\(=17\times\left(516-8\right)\)
\(=17\times508\)
\(=8636\)
------------
\(35\times215-35\times200-175\)
\(=35\times215-35\times200-35\times5\)
\(=35\times\left(215-200-5\right)\)
\(=35\times10\)
\(=350\)
------------
\(48\times56+28\times104\)
\(=48\times2\times28+28\times104\)
\(=28\times\left(48\times2+104\right)\)
\(=28\times200\)
\(=5600\)
rewrite the sentence that does not change :
1. lan hasn't written to Marian for a month
=> Lan...
2. He has lived in Ha Noi since last year
=> he began...
3. I haven't met her for a long time
=> It's...
4. How long have you learnt French ?
=> When...
5. How long have you bought this car ?
=> When...
rewrite the sentence that does not change :
1. lan hasn't written to Marian for a month
=> Lan.last wrote to Marian a month ago..
2. He has lived in Ha Noi since last year
=> he began.living in HN last year..
3. I haven't met her for a long time
=> It's.a long time since I last met her..
4. How long have you learnt French ?
=> When.did you learn French?..
5. How long have you bought this car ?
=> When..did you buy this car?.
Bài 1 tính nhanh
A) 37 x 46 + 37 x 51 + 111
B) 35x 215 -35 x 210 - 175
c) 172 x 47 + 86 x 8 - 34 x4
d) 48 x 56 + 28 x104
a) \(37\times46+37\times51+111\)
\(=37\times46+37\times51+37\times3\)
\(=37\times\left(46+51+3\right)\)
\(=37\times100\)
\(=3700\)
b) \(35\times215-35\times210-175\)
\(=35\times215-35\times210-35\times5\)
\(=35\times\left(215-210-5\right)\)
\(=35\times0\)
\(=0\)
c) \(172\times47+86\times8-34\times4\)
\(=4\times\left(43\times47+86\times2-34\right)\)
\(=4\times\left(2021+172-34\right)\)
\(=4\times2159\)
\(=8636\)
d) \(48\times56+28\times104\)
\(=48\times56+56\times52\)
\(=56\times\left(48+52\right)\)
\(=56\times100\)
\(=5600\)
So sánh -249/333 và -83/111
\(-\dfrac{249:3}{333:3}=-\dfrac{83}{111}\Rightarrow-\dfrac{249}{333}=-\dfrac{83}{111}\)