Verified answer

2,10,50....................,1250

a=2 r=5 n=1250

1250=2(5)^n-1

625=5^(n-1)

5^4=5^(n-1)

n-1=4

n=5

Hi Hasina

the standard term in a GP

Tn = a * r(n-1)

where a is the first term and r is the common difference

So 2*5n-1) = 1250

5^(n-1) = 625

Now 5^4 = 625

so

n-1 = 4

n = 5

Shy

2x 5 = 10

10x 5 = 50

50x5 = 250

250x5 = 1250

so n =5

Yes, that is how you do it. Solve your equation 2(5)^(n-1) = 1250 for n, and that--n--is the number of terms. You got the right idea!

625 = 5^(n - 1)

5^4 = 5^(n - 1)

4 = n - 1

n = 5