Answer:a=first term
d=common difference
here,a=85,d=-7
tn=a+(n-1)d
tn=85+(n-1)-7
tn=85+(7n+7)
92-7n=0
7n=92
n=92/7
n=13.14
n=13
Sn=(n/2)(2a+(n-1)d)
sn=13/2(2*85+(13-1)(-7)
sn=(170+(12*-7)
sn=170-84
sn=13/2*86
sn=559
Step-by-step explanation:looks like it is 7 minus previous number. So, unfortunately 7 does not divide into 85 nicely. 7*12 = 84. So, how every many numbers there are — does it stop at positive numbers only? If not, then it is negative infinity… .
85+78+71+64+57+50+43+36+29+22+15+8+1 = 559
p.s. I tried to be clever with summations (there are 13 numbers) and ran into trouble. Probably the ‘1’ at the end or the 85 at the beginning ... … 7*(summation of 1 to 13) plus an offset to account for the not divisible by 12 exactly. Didn’t work, and it was easier to just do the subtractions and add them together.
Answer:
part a: 45
part b: 102 and 68
Step-by-step explanation:
The correct one is option 1.sphere
The answer is The number 4
Answer: it is x=5/7 or x=-5/7
