Question

tìm x biết:

a,5^x=125

b,(x+1)+(x+2)+(x+3)+..........+(x+100)=5750

Answer 1

a)5^x=125

5^x=5^3

=> x=3

b) (x+1)+(x+2)+(x+3)+...+(x+100)=5750

(x+x+x+...+x)+(1+2+3+...+100)=5750

100x+5050=5750

100x=5750-5050

100x=700

x=700:100

x=7