Tính:
a. 12 x 13 x 14
b. 67 x 12 + 33 x 12
c. 100 x 12 + 100 x 88
tính bằng cách thuận tiện nhất
1235 x 6789 x ( 630 - 315 x 2 )
( 100 + 67 ) x 67 + ( 200 - 33 ) x 33
72 + 36 x 2 + 24 x 3 + 18 x 4 +12 x 2 +168
\(1235\text{×}6789\text{×}\left(630-315\text{×}2\right)\)
\(=1235\text{×}6789\text{×}\left(630-630\right)\)
\(=1235\text{×}6789\text{×}0=0\)
\(\left(100+67\right)\text{×}67+\left(200-38\right)\text{×}33\)
\(=167\text{×}67+167\text{×}33\)
\(=167\text{×}\left(67+33\right)\)
\(=167\text{×}100=16700\)
\(72+36\text{×}2+24\text{×}3+18\text{×}4+12\text{×}2+168\)
\(=72+72+72+72+24+168\)
\(=\left(72\text{×}4\right)+24+168=288+24+168=480\)
a) \(1235\times6789\times\left(630-630\right)\)
\(=1235\times6789\times0\)
\(=1235\times0\)
\(=0\)
b) \(167\times67+167\times33\)
\(=167\times\left(67+33\right)\)
\(=167\times100\)
=16700
a) (100 + 67) x 67 + (200 – 33) x 33 b) 45,651 x 73 + 45,651 x 20 + 45,651 x 7 c) 14,2 x 30 + 14,2 x 57 + 14,2 x 13 d) 72 + 36 x2 + 24 x 3 + 18 x 4 + 12 x 6 + 168 e) (8,27 + 7,16 + 9,333) – (7,27 + 6,16 + 8,33) | g) 1,5 + 2,5 + 3,5 + 4,5 +… + 8,5 h) 7,63 x 12,47 + 12,47 x 2,37 i) 37,2 x 101 – 37 – 0,2 k) 112,37 x 4,29 – 4,29 x 12,37 l) 17,4 x 52 + 57 x 17,4 – 17,4 x 9 i) 28 + 62 x a x ( a x 1 – a : 1) + 28 x 8 + 2 |
Bài 1 tìm x biết
a) 5x +5x+2=650
b)23x+2=4x+5
c)x-11/89 + x-12/88 + x-33/67 = x-67/33 + x-88/12 +x-89/11
d)4x-x-1=2x+3
Tính : ( 1 + 2 + ... + 100 ) x ( 1125 - 125 x 9 ) x ( 234 x 12 + 234 x 88 )
=(1+2+...+100)*(1125-1125)*(234*12+234*88)
=(1+2+...+100)*0*(234*12+234*88)
=0
Biểu diễn các hiệu sau thành tổng rồi tính:
a) \((-100) - 12\)
b) \(x + (-15) = -18\)
c) \((-14) - x + (-15) = 10 \)
d) \(x - (-19) - (-11) = 0\)
a/(-100)-12=-100+(-12)=-112
b/x=-18-(-15)=-18+15=-3
c/-14+x=10-(-15)=10+15=25
x=-14-25
x=-39
d.x-(-19)=0+(-11)=-11
x+19=-11
x=-11-19
x=-30
1.(x+1)/35 + (x+3)/33 = (x+5)/33 + (x+7)/20
2. (X+1)/12+ (X+2)/13 = (X+3)/14+ (X+4)/15
3. (X-85)/15+ (X-75)/13+(X-67)/11+ (X-64)/9=10
4. (X-1)/13-(2X-13)/15=(3X-15)/27- (4X-27)/29
2: \(\Leftrightarrow\left(\dfrac{x+1}{12}-1\right)+\left(\dfrac{x+2}{13}-1\right)=\left(\dfrac{x+3}{14}-1\right)+\left(\dfrac{x+4}{15}-1\right)\)
=>x-11=0
=>x=11
3: \(\Leftrightarrow\left(\dfrac{x-85}{15}-1\right)+\left(\dfrac{x-74}{13}-2\right)+\left(\dfrac{x-67}{11}-3\right)+\left(\dfrac{x-64}{9}-4\right)=0\)
=>x-100=0
=>x=100
Tìm số tự nhiên x,biết:
a)58 + 7x = 100
b) ( x –12):12=12
c) x -56 : 4= 16
d) 101 +(36 –4x) =105
e) 2(x-51) = 2.23+ 20
f) 10 -(x –3): 2 = 72–110
g) 2x –49 = 5.32h) [(8x -12) : 4].33= 36
i) 52x –3–2 . 52= 52. 3 k) (x3–7) : 4 = 5
a: 7x+58=100
nên 7x=42
hay x=6
c: x-56:x=16
nên x-14=16
hay x=30
c)x - 56 : 4 = 16
x - 56 = 16 : 4
x- 56 = 4
x =4 + 56
x = 60
d)101 + (36 - 4x) = 105
(36- 4x ) = 105 - 101
36 - 4x = 4
4x = 36 - 4
4x = 32
x = 32:4
x = 8
a) 58 + 7x = 100
7x = 100 - 58
7x = 42
x = 42 : 7
x = 6
b) (x - 12) : 12 = 12
x - 12 = 12 . 12
x - 12 = 144
x = 144 + 12
x = 156
Cau tinh nhanh sau 29+88+22+33+12+67+78+71 Thi minh se tinh nhung cap sau(29+71)+(88+12)+(22+78)+(33+67) . Nhung cap nay deu bang 100 neu khong phai tinh lau nhu 100+100+100+100 thi minh se lam phep tinh nhan 100x4 du gi thi 2 cap nay cunh bang 400.Minh tinh the co dung khong.
Đúng!!!Rất đúng!!!Anh lớp 5.Anh tin vậy.
tinh nhanh
a) (100 + 67) x 67 + (200 – 33) x 33
b) 45,651 x 73 + 45,651 x 20 + 45,651 x 7
c) 14,2 x 30 + 14,2 x 57 + 14,2 x 13
a) \(\left(100+67\right).67+\left(200-33\right).33\)
\(=167.67+167.33\)
\(=167.\left(67+33\right)\)
\(=167.100\)
\(=16700\)
b) \(45,651.73+45,651.20+45,651.7\)
\(=45,651.\left(73+20+7\right)\)
\(=45,651.100\)
\(=4565,1\)
c) \(14,2.30+14,2.57+14,2.13\)
\(=14,2.\left(30+57+13\right)\)
\(=14,2.100\)
\(=1420\)
_Chúc bạn học tốt_