Tìm x:
56/x=7 72/x=9 68*x=408 36*x=216
Tìm x biết:
a, (x + 72) × 4 = 320
b, (x - 56) × 7 = 749
c, (x + 3) × 4 = 36
d, (x - 5) × 6 = 72
tính bằng hai cách
786 x ( 32 + 68 )
2904 x 15 + 2904 x 35
436 x 72 - 436 x 42
194 x ( 87 - 7 )
3332 : ( 4 x 49 )
72 : 9 : 8
( 15 x 24 ) : 6
25 x ( 36 : 9 )
C1:
a. 786 x ( 32 +68)
= 786 x 100
= 78600
b. 2904 x 15 + 2904 x 35
= 43560 + 101640
= 145200
c.436 x 72 - 436 x 42
= 31392 - 18312
= 13080
d.194 x (87-7)
= 194 x 80
=15520
e.3332 : (4x49)
= 3332 : 196
= 17
f. 72 : 9 : 8
= (72 : 9) :8
= 1
g. (15 x 24) : 6
= 360 :6
= 60
m. 25 x(36 :9)
= 25 x 4
= 100
Cách 2:
a.786 x 32 + 786 x 68
= 25152 + 53448
= 78600
b. 2904 x ( 15 + 35)
= 2904 x 50
= 145200
c.436 x (72 -42)
= 436 x 30
= 13080
d.194 x 87 - 194 x7
= 16878 - 1358
= 15520
e. 3332 : (4 x 49)
= 3332 : 4 : 49
= 833 : 49 = 17
f. 72 : 9 :8
= 72 : (9 x8)
= 72 : 72
=1
g. (15 x 24) :6
= 15 x (24 :6)
= 15 x 4
= 60
m. 25 x (36 :9)
= ( 25 x36 ):9
= 900 : 9
=100
Tính nhanh :
a , 117 x 36 + 117 x 72 - 17 x 72 - 17 x 36
b,408 x 53 - 5 x 204 - 204
117 x 36 + 117 x 72 - 17 x 72 - 17 x 36
= ( 117 - 17 ) x 36 - ( 117 - 17 ) x 72
= 100 x 36 - 100 x 72
= 100 x ( 36 - 72 )
= 100 x -36
= -3600
____________________________________
408 x 53 - 5 x 204 - 204
= 408 x 53 - 5 x 204 - 204 x 1
= 408 x 53 - ( 5 - 1 ) x 204
= 408 x 53 - 4 x 204
= 21624 - 816
= 20808
Bài 3: Tìm x, biết:
a) 2 – x + 2x = -18 + (-22)
b) 6x – (7 + 2x) = -67 + 72
c) 68 – [56 – (-x)] = -2
mn giúp mình với ạ mình đang gấp ạ
\(a,\Rightarrow x+2=-40\\ \Rightarrow x=-42\\ b,\Rightarrow6x-7-2x=5\\ \Rightarrow4x=12\Rightarrow x=3\\ c,\Rightarrow68-56-x=-2\\ \Rightarrow12-x=-2\\ \Rightarrow x=14\)
Tính nhanh: a) ( 68 x 72 x 49) x ( 27 x 12 – 9 x 36 )
b) ( 25 x 50 – 125 x 10 ) x ( 1 + 2 + 3 + ……….. + 99 + 100
a: \(=68\cdot72\cdot49\cdot\left[324-324\right]=0\)
b: \(=\left(1250-1250\right)\cdot\left(1+...+100\right)=0\)
\(a,\left(68\times72\times49\right)\times\left(27\times12-9\times36\right)=\left(68\times72\times49\right)\times0=0\\ b,\left(25\times50-125\times10\right)\times\left(1+2+...+100\right)=0\times\left(1+2+...+100\right)=0\)
a, ( 68 × 72 × 49 ) × ( 27 × 12 − 9 × 36 ) = ( 68 × 72 × 49 ) × 0 =
b, ( 25 × 50 − 125 × 10 ) × ( 1 + 2 + ... + 100 ) = 0 × ( 1 + 2 + ... + 100 ) = 0
Tìm x
A x-56 x 24 = 286
B 65 x 54- x = 1026
C 36 x 84 : x= 72
X : 47 = 326 - 277
`@` `\text {Ans}`
`\downarrow`
`A.`
`x-56 \times 24 = 286`
`x-1344 = 286`
`x=286 + 1344`
`x=1630`
`B.`
`65 \times 54 - x = 1026`
`3510 - x =1026`
`x=3510 - 1026`
`x=2484`
`C.`
`36 \times 84 \div x = 72`
`3024 \div x = 72`
`x=3024 \div 72`
`x=42`
`D.`
`x \div 47 = 326 - 277`
`x \div 47 = 49`
`x= 49 \times 47`
`x=2303`
A. \(x-56\times24=286\\ x-1344=286\\ x=286+1344\\ x=1630\)
B. \(65\times54-x=1026\\ 3510-x=1026\\ x=3510-1026\\ x=2484\)
C. \(36\times84\div x=72\\ 3024\div x=72\\ x-3024\div72\\ x=42\)
D. \(x\div47=326-277\\ x\div47=49\\ x=49\times47\\ x=2303\)
36 x 5 + 72 x 2 - 216 + 144
bài 2 tìm x biết
a, - 9 . ( x - 6 ) + 20 = 56
b, ( 245 - x ) + 72 = 149
c, ( 2x- 3 ) . 7 = 35
giúp tui nhaaa
`- 9 . ( x - 6 ) + 20 = 56`
`=> -9 . ( x - 6 ) = 56-20`
`=> -9 . ( x - 6 ) =36`
`=>x-6=36:(-9)`
`=>x-6=-4`
`=>x=-4+6`
`=>x=2`
`-------------`
` ( 245 - x ) + 7^2=149`
`=>( 245 - x ) +49=149`
`=> 245 - x =149-49`
`=> 245 - x =100`
`=>x=245-100`
`=>x=145`
`------------`
`(2^x-3).7=35`
`=> 2^x-3=35:7`
`=> 2^x-3=5`
`=>2^x=5+3`
`=>2^x=8`
`=>2^x=2^3`
`=>x=3`
Tính bằng cách thuận tiện nhất 36 x 5 + 72 x 2 - 216 + 144
\(36\text{×}5+72\text{×}2-216+144\)
\(=36\text{×}5+36\text{×}2\text{×}2-36\text{×}6+36\text{×}4\)
\(=36\text{×}5+36\text{×}4-36\text{×}6+36\text{×}4\)
\(=36\text{×}\left(5+4-6+4\right)=36\text{×}7=252\)