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a) \(3119\cdot121-3119\cdot11\cdot11\)
\(=3119\cdot121-3119\cdot\left(11\cdot11\right)\)
\(=3119\cdot121-3119\cdot121\)
\(=3119\left(121-121\right)\)
\(=0\)
b) \(24\cdot\left(123\cdot87\right)+\left(87\cdot123\right)\cdot76\)
\(=\left(123\cdot87\right)\cdot\left(76+24\right)\)
\(=\left(123\cdot87\right)\cdot100\)
\(=1070100\)
a, 123 - ( 155 + 123 - 55 )
= 123 - 155 - 123 + 55
= 123 - 123 -155 + 55
= 0 - 155 + 55
= -155 + 55
= -100
b, -315 - ( -43 + 17 - 315 )
= -315 + 43 -17 + 315
= -315 + 315 + 43 -17
= 0 + 26 = 26
c. -15 .49 - 15. 51
= 15. -49 - 15 . 51
= 15 ( -49 - 51 )
= 15. ( -100 )
= -1500
d. -35 . 47 - 35 . 50 + 35 . -3
= 35 ( -47 - 50 + -3 )
=35. -100
= -3500
a, 123-(155+123-55)=123-223=-100
b,-315-(-43+17-315)=26
c,-15*49-15*51=-1500
d, -35.47-35.50+35.-3=-38.97
Lời giải:
$(-123)(87-53)-53(123-87)$
$=-123.87+123.53-53.123+53.87$
$=(-123.87+53.87)+(123.53-53.123)$
$=87(53-123)+0=87(-70)=-6090$
a; A = (32.5 - 160: 22) + 2024
A = (9.5 - 160 : 4) + 2024
A = (45 - 40) + 2024
A = 5 + 2024
A = 2029
b; B = (-360) - (-87) + 69 - 87
B = -360 + 87 + 69 - 87
B = - (360 - 69) + (87 - 87)
B = - 291 + 0
B = -291
c; C = 182.26 - 82.26 + 500
C = 26.(182 - 82) + 500
C = 26.100 + 500
C = 2600 + 500
C = 3100
a) \(645-\left(27+x\right)-342=123\)
\(\Leftrightarrow\)\(-24-x=123\)
\(\Leftrightarrow\)\(x=123+24=147\)
Vậy...
b) \(\left|x\right|+87=123\)
\(\Leftrightarrow\)\(\left|x\right|=123-87=36\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}x=36\\x=-36\end{cases}}\)
Vậy....
c) \(\left|x-12\right|=42\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}x-12=42\\x-12=-42\end{cases}}\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}x=54\\x=-30\end{cases}}\)
Vậy...
a) 645 - ( 27 + x ) - 342 = 123
645 - ( 27 + x ) = 123 + 342
645 - ( 27 + x ) = 465
27 + x = 645 - 465
27 + x = 180
x = 180 - 27
x = 53
b) ! x ! + 87 = 123
! x ! = 123 - 87
! x ! = 36
-> x = 36 hoặc x = -36
c) ! x - 12 ! = 42
-> x - 12 = 42 hoặc x - 12 = -42
Nếu x - 12 = 42 thì ta có : Nếu x - 12 = -42 thì ta có :
x = 42 + 12 x = -42 + 12
x = 54 x = -30
\(a,30\cdot6+30\cdot71+20\cdot30\)
=\(30\cdot\left(6+71+20\right)\)
=\(30\cdot97=2910\)
\(b,24\cdot\left(31+119\right)+76\cdot\left(29+121\right)\)
=\(24\cdot150+76\cdot150\)
=\(150\cdot\left(24+76\right)\)
=\(150\cdot100\)
=\(15000\)
\(c,87\cdot23+70\cdot87+43\cdot93\)
=\(87\cdot\left(23+87\right)+43\cdot93\)
=\(87\cdot110+3999\)
=\(9570+3999\)
=13569
a) 15 . 6 . 2 + 3 . 71 . 10 + 20 . 30
= ( 15 . 2 ) . 6 + ( 3 . 10 ) . 71 + 20 . 30
= 30 . 6 + 30 . 71 + 20 . 30
= 30 . ( 6 + 71 + 30 )
= 30 . 107
= 3210
b) 24 . 31 + 24 . 119 + 76 . 29 + 76 . 121
= 24 . ( 31 + 119 ) + 76 . ( 29 + 121 )
= 24 . 150 + 76 . 150
= 150 . ( 24 + 76 )
= 150 . 100
= 15 000
c) 87 . 23 + 43 . 93 + 70 . 87
= 87 . 23 + 70 . 87 + 43 . 93
= 87 . ( 23 + 70 ) + 43 . 93
= 87 . 93 + 43 . 93
= 93 . ( 87 + 43 )
= 93 . 130
= 12 090
a) 17.88 + 17.12
= 17. (88 + 12)
= 17.100
= 1 700.
b) 25.32 + 4.92.25
= 25.(32 + 4.92)
= 25.(32 + 368)
= 25.400
= 10 000.
c) 3 119.121 - 3 119.11.11
= 3 119.121 - 3 119.121
= 3 119(121 – 121)
= 3 119.0
= 0.
d) 24.(123 + 87) + (87 + 123).76
= 24.210 + 210.76
= 210.(24 + 76)
= 210. 100
= 21 000.