3 · 42x+1 − 156 = 72 : 2
(2400+4600)-3.x=1200
[(6.x-72):2-84 ] .28=5628
42x=39.42-37.42
Bài 1.
a) - 12 - ( - 46 )
b) - ( - 8 ) - 54
c) - 15 - ( - 72 )
Bài 2. Bỏ ngoặc rồi tính
a) ( 156 - 812 ) - ( 156 - 12 )
b) - ( - 72 + 83 ) - ( 72 + 17 )
c) - ( - 23 - 78 ) + ( 77 - 178 )
d) ( - 213 - 156 ) - ( - 213 + 44 ) Giúp em 2 bài này với ạ
Bài 1:
a.
$-12-(-46)=-12+46=46-12=34$
b.
$-(-8)-54=8-54=-(54-8)=-46$
c.
$-15-(-72)=-15+72=72-15=57$
Bài 2:
a. $(156-812)-(156-12)=156-812-156+12$
$=(156-156)-(812-12)=0-800=-800$
b.
$-(-72+83)-(72+17)=72-83-72-17=(72-72)-(83+17)$
$=0-100=-100$
c.
$-(-23-78)+(77-178)=23+78+77-178$
$=(23+77)-(178-78)=100-100=0$
d.
$(-213-156)-(-213+44)=-213-156+213-44=(-213+213)-(156+44)$
$=0-200=-200$
tim x
1/5 + 2/30 + 121/165 < hoặc = x < hoặc = 1/2 + 156/72 + 1/3
tìm x
a. 120 + ( 56 - 2x ) .3 = 156
b. 3x - 2^3 = 3^2 + 1^21
c. [( 6x - 72 ) : 2 - 84] 28 = 5628
[(6x - 72) : 2 - 84]. 28 = 5628
=> (6x - 72) : 2 - 84 = 5628 : 28 = 201
=> (6x - 72) : 2 = 201 + 84 = 285
=> 6x - 72 = 285 . 2 = 570
=> 6x = 570 + 72 = 642
=> x = 642 : 6
=> x = 107
\(120+\left(56-2x\right).3=156\)
\(\left(56-2x\right).3=156-120\)
\(\left(56-2x\right).3=36\)
\(56-2x=36:3\)
\(56-2x=12\)
\(2x=56-12\)
\(2x=44\)
\(x=44:2\)
\(x=22\)
Tim so tu nhien x biet :
A,(2600+6400)-3×x=1200
B,[(6×x-72):2-84].28=5628
C,2x-138=2^3÷3^2
d,42x=39×42-37×42
Dup minh nhe
\(a,\left(2600+6400\right)-3\times x=1200\)
\(9000-3\times x=1200\)
\(3\times x=9000-1200\)
\(3\times x=7800\)
\(x=7800:3\)
\(x=2600\)
\(b,\left[\left(6\times x-72\right):2-84\right]\times28=5628\)
\(\left(6\times x-72\right):2-84=5628:28\)
\(\left(6\times x-72\right):2-84=201\)
\(\left(6\times x-72\right):2=201+84\)
\(\left(6\times x-72\right):2=285\)
\(6\times x-72=285\times2\)
\(6\times x-72=570\)
\(6\times x=570+72\)
\(6\times x=642\)
\(x=107\)
\(c,2x-138=2^3:3^2\)
\(2x-138=\frac{8}{9}\)
\(2x=\frac{8}{9}+138\)
\(2x=\frac{1250}{9}\)
\(x=\frac{1250}{9}:2\)
\(x=\frac{625}{9}\)
\(d,42x=39\times42-37\times42\)
\(42x=42\times\left(39-37\right)\)
\(42x=42\times2\)
\(42x=84\)
\(x=2\)
Tìm số tự nhiên x, biết:
a) (2600 + 6400) - 3 . x = 1200
b) [(6 . x - 72) : 2 -84] . 28 = 5628
c) 2x - 138 = 23 . 32
d) 42x = 39 . 42 - 37 . 42
ai cho 2 cái để được hai điểm hỏi đáp
tìm số tự nhiên x biết
a) ( 2600 +6400 ) -3 x X =1200
b) [ ( 6x X -72 ) : 2 -84 ] x 28 =5628
c) 2x -138 = 23 x 32
d) 42x =39 x 42 - 37 x 42
tìm số tự nhiên x biết
a) ( 2600 +6400 ) -3 x X =1200
b) [ ( 6x X -72 ) : 2 -84 ] x 28 =5628
c) 2x -138 = 23 x 32
d) 42x =39 x 42 - 37 x 42
Bài 1: Tính một cách hợp lí:
1) 2155 - ( 174 + 2155 ) + ( -68 + 174 ) 7) -1911 - ( 1234 - 1911 )
2) -25 . 72 + 25 . 21 - 49 . 25 8) 156 . 72 + 28 . 156
3) 35 . ( 14 - 23 ) - 23 . ( 14 - 35 ) 9) 32. ( -39 ) + 16 . ( -22 )
4) 8154 - ( 674 + 8154 ) + ( -98 + 674 ) 10) -1945 - ( 567 - 1945 )
5) -25 . 21 + 25 . 72 + 49 . 25 11) 184 . 33 + 67 . 184
6) 27 . ( 13 - 16 ) - 16 . ( 13 - 27) 12) 44 . ( -36 ) + 22 . ( -28 )
1) 2155-(174+2155)+(-68+174-7)-1911-(1234-1911)
=2155-174-2155+(-68)+174-7-1911-1234+1911
=(2155-2155)+(174-174)+(1911-1911)-(68+7+1234)
= 0 + 0 + 0 - 1309
= -1309