Question

Tìm x:

 1+3+5+7+9+....+(2x-1)=225

Answer 1

1 + 3 + 5 + 7 + ... + ( 2x - 1 ) = 225

=> ( 1 + 2n - 1 ) . n : 2 = n²

Suy ra 1 + 3 + 5 + 7 + ... + ( 2x - 1 ) = n²

Ta có : 225 = 3² . 5² = ( 3 . 5 )² = 15²

Vậy n = 15

Answer 2

1 + 3 + 5 + 7 + 9 + ... + (2x - 1) = 225

=> (1 + 2n - 1) . n : 2 = n²

Suy : 1 + 3 + 5 + 7 + 9 + ... (2x - 1) = n²

Có : 225 = 3² . 5² = (3.5)² = 15²

Vậy : n = 15

nhớ tick á  

Answer 3

X=15

Answer 4

1 + 3 + 5 + 7 + ... + ( 2x - 1 ) = 225

=> ( 1 + 2n - 1 ) . n : 2 = n²

Suy ra 1 + 3 + 5 + 7 + ... + ( 2x - 1 ) = n²

Ta có : 225 = 3² . 5² = ( 3 . 5 )² = 15²

Vậy n = 15

Answer 5

1 + 3 + 5 + 7 + ... + (2x - 1) = 225

 

=> (1 + 2n - 1) . n : 2 = n2

 

=> 1 + 3 + 5 + 7 +  ... + (2x - 1) = n2

 

Có  225 = 32 . 52 = (3.5)2 = 152

 

Vậy  n = 15

Answer 6

Quên viết mũ ạ nhưng đừng quyên tick cho mình nhá

Answer 7

1 + 3 + 5 + 7 + 9 + ... + (2x - 1) = 225

=> (1 + 2n - 1) . n : 2 = n²

Suy : 1 + 3 + 5 + 7 + 9 + ... (2x - 1) = n²

Có : 225 = 3² . 5² = (3.5)² = 15²

Vậy : n = 15

Answer 8

\(1+3+5+7+9+...+(2x-1)=225\)

\(\rArr(1+2x-1).x\colon2=x^2\)

\(1+3+5+7+9+...+(2x-1)=x^2\)

\(\rArr225=3^2.5^2=(3.5)^2=15^2\)

\(\rArr x=15\)

❤ΩΩΩ❤

Answer 9

1 + 3 + 5 + 7 + ... + ( 2x - 1 ) = 225

=> ( 1 + 2n - 1 ) . n : 2 = n²

Suy ra 1 + 3 + 5 + 7 + ... + ( 2x - 1 ) = n²

Ta có : 225 = 3² . 5² = ( 3 . 5 )² = 15²

Vậy n = 15

Answer 10

S O S