Question

tìm x:

2952:[151-(15x - 2)]=24

1+2+3+4+...+x=465

Answer 1

2952:[151-(15x-2)]=24

<=>151-(15x-2)= 2952: 24

<=>151-(15x-2) =123

<=>15x-2= 151-123

<=>15x-2= 28

<=>15x= 28+2

<=>15x= 30

<=>x= 30: 15

<=>=2

Vậy x=2

Answer 2

 

1+2+3+4+5+...+x=465

(x+1)x:2=465

x(x+1)=465.2

x(x+1)=930

x(x+1)=2.3.5.31

x(x+1)=30.31

=>x=30.

Answer 3

`2952:[151−(15x−2)]=24`

`⇔151−(15x−2)=2952:24`

`⇔151−(15x−2)=123`

`⇔15x−2=151−123`

`⇔15x−2=28`

`⇔15x=28+2`

`⇔15x=30`

`⇔x=30:15`

`⇔x=2`

Ta có:

`1+2+3+...+x= 465`

Số số hạng là : `(x-1): 1 + 1 = x`(số) 

`=> x(x+1): 2= 465`

`=> x(x+1)    = 930`

`=> x(x+1)    = 30.31`

`=>  x= 30 `