23-x=3
tính thuận tiện
23 + 23 x2 + 23 x 3 + 23 x 4
23+23*2+23*3+23*4
=23*1+23*2+23*3+23*4
=23*(1+2+3+4)
=23*10
=230
23 + 23 x 2 + 23 x 3 + 23 x 4
= 23 x ( 1 + 2 + 3 + 4 )
= 23 x 10
= 230
23+23x2+23x3+23x4
=23x(1+2+3+4)
=23x10
=230
k mik nha
BT: tìm x
1) 15- (- x - 3)= -38-22
2) -( x-23) + 18 = -x + (23 - x)
3) - (x-25)={ 48- [ 56 - (23 - 38 )] }
a, \(15-\left(x-3\right)=-38-22\)
\(15-\left(x-3\right)=-60\)
\(x-3=15-\left(-60\right)\)
\(x-3=75\)
\(x=78\)
Tính nhanh :
23 + 23 x 2 + 23 x 3 + 23 x 4
246 x 2005 - 2005 x 148
25 x 12 x 30 x 4
23 + 23 x 2 + 23 x 3 + 23 x 4
= 23 x (1 + 2 + 3 + 4)
= 23 x 10
= 230
246 x 2005 - 2005 x 148
= (246 - 148) x 2005
= 98 x 2005
= 196490
25 x 12 x 30 x 4
= (25 x 4) x 12 x 30
= 100 x 360
= 36000
233 + 23 x 2 + 23 x 3 + 23 x 4
= 23 x ( 1 + 2 + 3 + 4 )
= 23 x 10
= 230
246 x 2005 - 2005 x 148
= ( 246 - 148 ) x 2005
= 98 x 2005
= 196490
25 x 12 x 30 x 4
= ( 25 x 4 ) x ( 12 x 30 )
= 100 x 360
= 36000
2/3 x 5/19 + 2/23 x 3/19 + 2/23 x 11/19
`@` `\text {Ans}`
`\downarrow`
\(\dfrac{2}{23}\times\dfrac{5}{19}+\dfrac{2}{23}\times\dfrac{3}{19}+\dfrac{2}{23}\times\dfrac{11}{19}?\)
`=`\(\dfrac{2}{23}\times\left(\dfrac{5}{19}+\dfrac{3}{19}+\dfrac{11}{19}\right)\)
`=`\(\dfrac{2}{23}\times\dfrac{19}{19}\)
`=`\(\dfrac{2}{23}\times1=\dfrac{2}{23}\)
\(\dfrac{2}{3}\) \(\times\) \(\dfrac{5}{19}\) + \(\dfrac{2}{23}\)\(\times\)\(\dfrac{3}{19}\) + \(\dfrac{2}{23}\) \(\times\) \(\dfrac{11}{19}\)
= \(\dfrac{2}{3}\) \(\times\) \(\dfrac{5}{19}\) + \(\dfrac{2}{23}\) \(\times\) ( \(\dfrac{3}{19}\) + \(\dfrac{11}{19}\))
= \(\dfrac{2}{3}\) \(\times\) \(\dfrac{5}{19}\) + \(\dfrac{2}{23}\) \(\times\) \(\dfrac{14}{19}\)
= \(\dfrac{2}{19}\) \(\times\) ( \(\dfrac{5}{3}\) + \(\dfrac{14}{23}\))
= \(\dfrac{2}{19}\) \(\times\) \(\dfrac{157}{69}\)
= \(\dfrac{314}{1311}\)
Tính rồi so sánh giá trị của hai biểu thức (theo mẫu).
a) 23 x (7 - 4) và 23 x 7 - 23 x 4
b) (8 - 3) x 9 và 8 x 9 - 3 x 9
a,
23 x (7 - 4) = 23 x 3 = 69
23 x 7 - 23 x 4 = 161 - 92 = 69
Ta có: 23 x (7 - 4) = 23 x 7 - 23 x 4
b,
(8 - 3) x 9 = 5 x 9 = 45
8 x 9 - 3 x 9 = 72 - 27 = 45
Ta có: (8 - 3) x 9 = 8 x 9 - 3 x 9
So sánh x và y nếu:
a) x − 2 3 ≤ y − 2 3 b) − 3 − x > − y − 3 .
\(\dfrac{3}{4}\) x 36 + 75% x 23 + \(\dfrac{75}{100}\) + 0,75 x 40
= ..... x 36 + ....... x 23 + ..... + 0,75 x 40
= ..... x ( 36 + 23 + 1 + ..... )
= ..... x 100
= .....
23 x X [ ( 12 x X + 39 ) ] : 3 = 23 + 40 x 115
Ta có: 23. [(12.X+39):3] = 4623
⇒(12.X+39):3 = 201
⇒12.X+39 = 603
⇒12.X = 564
⇒X = 47
Tìm x, biết x là số tự nhiên và: (1/1*3+1/3*5+...+1/23*25)*((x+1)+(x+3)+(x+5)+...(x+23)=144
`(1/(1.3)+1/(3.5)+.......+1/(23.25))xx((x+1)+(x+3)+(x+5)+.....+(x+23))=144`
`(2/(1.3)+2/(3.5)+.......+2/(23.25))xx[(x+x+....+x)+(1+3+5+...+23)]=288`
`(1-1/3+1/3-1/5+.....+1/23-1/25)xx(12x+(24.12)/2)=288`
`(1-1/25)xx(12x+12.12)=288`
`24/25xx[12(x+12)]=288`
`24/25xx(x+12)=28`
`x+12=28:24/25=50`
`x=50-12=38`
Vậy `x=38`
a 246 x 2005 - 2005 x 148
b 25 x 12 x 30 x 4
c 23 + 23 x 2 + 23 x 3 + 23 x 4
Nhiều nhỉ
Mong các bn giúp mình
a. 246 x 2005 - 2005 x 148
= (246 - 148) x 2005
= 98 x 2005
= 196490
b. 25 x 12 x 30 x 4
= (25 x 4) x 12 x 30
= 100 x 360
= 36000
c. 23 + 23 x 2 + 23 x 3 + 23 x 4
= 23 x 1 + 23 x 2 + 23 x 3 + 23 x 4
= 23 x (1 + 2 + 3 + 4)
= 23 x 10
= 230
a, 246x2005-2005x148
=(246-148)x2005
=98x2005
=196490
b, 25x12x30x4
=(25x4)x(12x30)
=100x360
=36000
c, 23+23x2+23x3+23x4
=23x(1+2+3+4)
=23x10
=230