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-27 + 5( x-7 ) = 23 - (71-3x)
-27 + 5( x-7 ) = 23 - 71 + 3x
5(x-7) - 3x = 23 - 71 + 27
5x - 35 - 3x = -21
x( 5-3 ) - 35 = -21
x.2 - 35 = -21
x.2 = -21 + 35
x.2 = 14
x = 7
Vậy x = 7
-27+5(x-7)=23-(71-3x)
=>-27+5x-35=23-71+3x
=>-27-35-23+71=3x-5x
=>-14=-2x
=>-2x=-14
=>x=-14:(-2)
=>x=7
Vậy x=7
\(a,30\cdot6+30\cdot71+20\cdot30\)
=\(30\cdot\left(6+71+20\right)\)
=\(30\cdot97=2910\)
\(b,24\cdot\left(31+119\right)+76\cdot\left(29+121\right)\)
=\(24\cdot150+76\cdot150\)
=\(150\cdot\left(24+76\right)\)
=\(150\cdot100\)
=\(15000\)
\(c,87\cdot23+70\cdot87+43\cdot93\)
=\(87\cdot\left(23+87\right)+43\cdot93\)
=\(87\cdot110+3999\)
=\(9570+3999\)
=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
Lời giải:
a.
$(x-15).27=0$
$x-15=0:27=0$
$x=15+0=15$
b.
$23(42-x)=0$
$42-x=0$
$x=42$
c.
$(9x+2).3=60$
$9x+2=60:3=20$
$9x=18$
$x=2$
d.
$71+(26-3x):5=75$
$(26-3x):5=75-71=4$
$26-3x=4.5=20$
$3x=26-20=6$
$x=6:2=3$
a) (71+x)-(-24-x)+(-35-x)=0 b)x-34-[(15+x)-(23-x)]=0
71+x+24+x+-35-x =0 x-34-15-x-23+x =0
(x+x-x)+(71+24-35) =0 (x-x+x)+(-34-15-23) =0
x+60 =0 x+-72 =0
x =0-60 x =0-(-72)
x = -60 x = 72
a/ M = (71+x)-(-24+x)+(-35-x) = 71 + x + 24 - x - 35 - x = (71 + 24 - 35) - x = 95 - 35 - x = 60 - x
b/ N=x-34-[(15+x)-(23-x)] = x - 34 - (15 + x - 23 + x) = x - 34 - (-8 + 2x) = x - 34 + 8 - 2x = -26 - x
\(a,M=\left(71+x\right)-\left(-24+x\right)+\left(-35-x\right)\)
\(=71+x+24-x-35-x\)
\(=60-x\)
\(b,N=x-34-\left[\left(15+x\right)-\left(23-x\right)\right]\)
\(=x-34-\left(15+x-23+x\right)\)
\(=x-34-15-x+23-x\)
\(=-26-x\)
mk chỉ làm ý A thui nha
\(A=\left(71+x\right)-\left(-24-x\right)+\left(-35-x\right)\)
\(A=71+x+24+x+\left(-35\right)-x\)
\(A=\left[71+24+\left(-35\right)\right]+\left(x+x-x\right)\)
\(A=60+x\)
Vậy \(A=60+x\)
\(a,A=\left(71+x\right)-\left(-24-x\right)+\left(-35-x\right)\)
\(=71+x+24+x-35-x\)
\(=60+x\)
\(b,B=x-34-\left[\left(15+x\right)-\left(23-x\right)\right]\)
\(=x-34-\left(15+x-23+x\right)\)
\(=x-34-15-x+23-x\)
\(=-x-26\)
a) ( 71 + x ) - ( -24 - x ) + ( -35 - x )
= 71 + x + 24 + x - 35 - x
= ( 71 + 24 - 35 ) + ( x + x - x )
= 60 + x
b) x - 34 - [( 15 + x ) - ( 23 - x )]
= x - 34 - ( 15 + x - 23 + x )
= x - 34 - ( 15 - 23 + x2 )
= x - 34 - ( - 8 + 2x )
= x - 34 + 8 - 2x
= x - 2x + 8 - 34
= -x - 26
c) ( -15 + |x| ) + ( -25 - |x| )
= -15 + |x| - 25 + |x|
= -15 - 25 + x + x
= -40 + x2
a)(71+x)-(-24-x)+(-35-x)
=>71+x+24+x-35-x
=>60+x
b)x-34-[(15+x)-(23-x)]
=>x-34-(15+x-23+x)
=>x-34-15-x+23-x
=-x-26
a/ (71+x) - [(-24) - x] + [(-35) - x ]=71+x+24+x-35-x=x+60
b/ x - 34 - [(15 + x) - (23 - x)]=x-34-15-x-23+x=x-72
c/ 26 - [(-x) + 126 - 13) + [(-113) + x]=26+x-126+13-113+x=2x-200=2(x-100)
71-24+3x=23
3x=23-71-24
3x=-24
x=-8
Vậy x=-8
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