Question

Tìm x biết (xEN)

a) x+1+x+3+x+5+....+x+35=360

b) x²+2+x²+4+x²+6+....+x²+28=336

Answer 1

a) `x+1+x+3+...+x+35=360`

`=> (x+x+...+x)+(1+3+...+35)=360`

`=> 18x+324=360`

`=> 18x=36`

`=>x=2`

b) `x^2+2+x^2+4+...+x^2+28=336`

`=> (x^2+x^2+...+x^2)+(2+4+...+28)=336`

`=> 14x^2+210=336`

`=>14x^2=126`

`=> x^2=9`

`=> x=3`

Answer 2

a: =>18x+324=360

=>18x=36

hay x=2

b: =>14x²+210=336

=>14x²=126

=>x²=9

=>x=3