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d) 12x 156 - 12 x 55 - 12
= 12 x ( 156 - 55 - 12 )
= 12 x 100
= 1200
e ) 12 x 11 + 21 x 11 + 11 x 33
= ( 12+ 21 + 33) x 12
= 66 x 11
= 726
g) 132 x 11 - 11 x 32 - 54 x 11
= ( 132 - 32 - 54 ) x 11
= 46 x 11
= 506
d) 12 x 156 - 12 x 55 - 12 = 12x(156 - 55 - 1 ) = 12 x 100 = 1200
e) 12 x 11 + 21 x 11 + 11 x 33 = 11 x ( 12 + 21 + 33 ) = 11 x 66 = 726
g) 132 x 11 - 11 x 32 - 54 x 11 = 11 x ( 132 - 32 - 54 ) = 11 x 46 = 506
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=>Xx (5+7+4-2-3)=x+90
=>Xx11=X+90
=>Xx11-X=90
=>Xx(11-1)=90
=>Xx10=90
=>X=9
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Trả lời :
( X + 1 ) + ( X + 2 ) + ( X + 3 ) + ( X + 4 ) + ( X + 5 ) = 90
=> ( X + X + X + X + X ) + ( 1 + 2 + 3 + 4 + 5 ) = 90
=> ( X x 5 ) + 15 = 90
=> X x 5 = 90 - 15
=> X x 5 = 75
=> X = 75 : 5
=> X = 15.
Vậy X = 15.
Học tốt nha~
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(x+1)+(x+2)+(x+3)+(x+4)+(x+5)=90
x+1+x+2+x+3+x+4+x+5=90
5x+(1+2+3+4+5)=90
5x+15=90
5x=90-15
5x=75
x=75:5
x=15
Bạn kia áp dụng công thức sai rồi nhé
\(1+2+3+....+n=\frac{n\left(n+1\right)}{2}\)
\(\left(X+1\right)+\left(X+2\right)+\left(X+3\right)+\left(X+4\right)+\left(X+5\right)=90\)
\(\left(X+X+X+X+X\right)+\left(1+2+3+4+5\right)=90\)
\(5X+\frac{5\left(5+1\right)}{2}=90\)
\(5X+15=90\)
\(5X=75\)
\(X=5\)
Vậy X=5
Kagura:Bạn nên nhớ là lớp 4 chưa học dấu <=> nhé !
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X : 4 x 20 + X : 5 x 15 + X :7 x 14 = 90
X x (20 : 4) + X x (15 : 5) + X x (14 : 7) = 90
X x 5 + X x 3 + X x 2 = 90
X x (5 + 3 + 2) =90
X x 10 = 90
X = 90 : 10
X = 9
Vậy X = 9
mình xin lỗi, bước 2 phải là:
X x 20 : 4 + X x 15 : 5 + X x 14 : 2
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\(100\cdot90\cdot60\cdot77\cdot100=100^2\cdot90\cdot60\cdot77\)
\(=4158000000\)(4 tỉ 158 triệu)
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a) (42+36):x=66
78:x=66
x=78:66
x=13/11
b) 90:x-48:x=3
(90-48):x=3
42:x=3
x=42:3
x= 14
a) 42:x+36:x=66
42.1/x+36.1/x=66
1/x.(42+36)=66
1/x=11/13
x=1:11/13
x=13/11
b) 90:x-48:x=3
90.1/x-48.1/x=3
1/x(90-48)=3
1/x=1/14
x=14
Ta có:
Xx11=X+90
=> Xx10=90
=> x=9