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
