Question

tìm x

 a) (x+15)-5=(-6)+(-8)+25 

b) 1+2+3+...+x = 55

 

Answer 1

a. (x + 15) - 5 = (-6) + (-8) + 25

=> x +15 - 5 = 11

=> x + 10 = 11

=> x = 11 - 10

=> x = 1

b. \(1+2+3+...+x=55\)

=> \(\frac{\left(x+1\right).x}{2}=55\)

=> (x+1).x=55.2

=> (x+1).x=110

=> (x+1).x=(10+1).10

=> x=10.

Answer 2

a) (x+15)-5=(-6)+(-8)+25

=>(x+15)-5=11

=>x+15    =11+5

=>x+15    =16

=>x         =16-15

=>x         =1

b) 1+2+3+...+x=55

=>(x+1).x:2=55

=>(x+1).x=55.2

=>(x+1).x=110

=>110=(10+1).10=(x+1).x

vậy x=10

Answer 3

Cảm ơn các bạn nhìu nhé ! Arigato codo saimat