Question

x+(x+1)+(x+2)+...+(x+30) = 1240

Trả lời chi tiết cho mình nhé

Answer 1

= x.30+x+[(1+30).30:2]=1240

=> x.31+31.30:2=1240

=> x.31+930:2=1240

=> x.31+465=1240

=> x.31=1240-465

=> x.31=775

=> x=775:31

=> x=25

Answer 2

x+(x+1)+(x+2)+(x+3)+.....+(x+30) = 1240
31.x+(1+2+3+4+5+...+29+30)=1240
31.x+31.15=1240
31.x=1240-31.15
31.x=775
x=775:31
x=25

Tick nhé