Answer:

It has one solution
Step-by-step explanation:
![14x + 12] = 0\\\\14x+12=0\\\mathrm{Subtract\:}12\mathrm{\:from\:both\:sides}\\14x+12-12=0-12\\\\Simplify\\14x=-12\\\\\mathrm{Divide\:both\:sides\:by\:}14\\\frac{14x}{14}=\frac{-12}{14}\\\\Simplify\\x=-\frac{6}{7}](https://tex.z-dn.net/?f=14x%20%2B%2012%5D%20%3D%200%5C%5C%5C%5C14x%2B12%3D0%5C%5C%5Cmathrm%7BSubtract%5C%3A%7D12%5Cmathrm%7B%5C%3Afrom%5C%3Aboth%5C%3Asides%7D%5C%5C14x%2B12-12%3D0-12%5C%5C%5C%5CSimplify%5C%5C14x%3D-12%5C%5C%5C%5C%5Cmathrm%7BDivide%5C%3Aboth%5C%3Asides%5C%3Aby%5C%3A%7D14%5C%5C%5Cfrac%7B14x%7D%7B14%7D%3D%5Cfrac%7B-12%7D%7B14%7D%5C%5C%5C%5CSimplify%5C%5Cx%3D-%5Cfrac%7B6%7D%7B7%7D)
Answer:
15
proof on pic......................
Answer: Choice A
S9 = (9/2)*(2+26)
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The formula is
Sn = (n/2)*(a1+an)
where
Sn = sum of the first n terms (nth partial sum)
n = number of terms
a1 = first term
an = nth term
In this case,
n = 9
a1 = 2 (plug in n = 1 into the formula an = 3n-1 and simplify)
an = a9 = 26 (plug n = 9 into the formula an = 3n-1 and simplify)
So,
Sn = (n/2)*(a1+an)
S9 = (9/2)*(2+26)
will help us find the sum of the first 9 terms of this arithmetic sequence