Question

What is the sum of the first 10 terms of the geometric sequence 1 , -2, 4, -8, 16, 32...​

Answer 1

Answer:

S10= -341

Step-by-step explanation:

1,-2,4,-8,16,.......

Sum of first 10 terms of geometric sequence

Sn=a(r^n-1)/r-1

where, a= first term

n= number of terms

r=common ratio

common ratio (r)= second term/first term

r=-2/1

r=-2

a=first term

a=1

n= number of terms

n=10

S10=1[(-2)^10-1]/-2-1

S10=(1024-1)/-3

S10=1023/-3

S10= -341

therefore, the sum of the first 10 terms is -342