Answer:
The value of n is complex
Step-by-step explanation:
The sequence is an arithmetic sequence
Given
First term a = -10
common diff d = -7-(-10) = -4-(-7) = 3
Sn = -104
get the number of terms n using the formula
Sn = n/2[2a+(n-1)d]
-104 = n/2[2(-10)+(n-1)(3)]
-104 = n/2[-20+3n-3]
-208 = n{3n-23}
-208 = 3n²-23n
3n²-23n+208 = 0
Factorize
n = 23±√23²+4(3)(208)/2(3)
n = 23±√529-2496/6
Since the value of n is a complex number, hence the value of n does not exist
