Question

Tìm x :
a ) 7 ( x-4 ) = 7⁴ : 73
b ) 2x-105 : 21=15
c ) 15-5 ( x- 1 ) = 10
d )  ( x-12 ) :3 = 6
e ) 24 + 5 . x = 7⁵ : 7³
g ) x + 12.3=40
h ) 2x-138=2³.3²
i ) 231- ( x-6 ) = 1339 : 13
k ) 3x + 2x = 25
l )  2x-4² : 8 = 12
m ) 12 ( x-1 ) :3=4³- 2³
n ) 128 : ( x-1 )² =2
o ) x-34=2.3²-1
ô ) 3+2^x-1 = 24 - [ 4² -(2²-1 ) ]
Viết gọn tổng sau :
A = 3+3²⁺ 3³ + 3⁴+......+3⁹⁹+3¹⁰⁰
So sanh :

 A = 1=2+2²+2³+2⁴+.....+2⁴⁹ và 2⁵⁰

 

Answer 1

Nhìu thế

Answer 2

Câu a:

7.(\(x-4\)) = \(7^4:7^3\)

7.(\(x-4\) )=7

(\(x-4\) )=7 : 7

(\(x-4\) )=1

\(x\) = 1+4

\(x\) = 5

Vậy \(x=5\)

Answer 3

\(2x-105:21=15\)

\(2x-5=15\)

\(2x\) =15 + 5

\(2x\) =20

\(x\) = 20 : 2

\(x\) = 10

Vậy \(x=10\)

Answer 4

c) 15 - 5(\(x\) -1)= 10

5(\(x\) -1) = 15 - 10

5(\(x\) -1)= 5

\(x\) -1 = 5:5

\(x\)- 1 = 1

\(x\) = 1+1

\(x\) =2

Vậy \(x=2\)

d)\(\left(x-12\right):3=6\)

\(x-12=6.3\)

\(x-12=18\)

\(x=12+18\)

\(x=30\)

Vậy \(x=30\)

Answer 5

e)\(24+5.x=7^5:7^3\)

\(24+5.x=7^2\)

\(24+5x=49\)

\(5x=\) 49 - 24

\(5x=25\)

\(x=25:5\)

\(x=5\)

vậy \(x=5\)

g)\(x+12.3=40\)

\(x+36=40\)

\(x=40-36\)

\(x=4\)

Vậy \(x=4\)