What is the equation for a geometric sequence with a first term of 5 and a second term of −10?

an = 5(−2)n − 1
an = 5(2)n − 1
an = 5(−15)n − 1
an = 5(15)n − 1

A is correct, an = 5(−2)n − 1

Step-by-step explanation:

The formula for geometric sequences is an=a(r)^n-1

a is the first term, which is 5 in this case

r is the common ratio, which is -2 because (5)(-2)=-10

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.