Answer:
465
Step-by-step explanation:
Since we are looking for the the number of combinations to have 2 different flavors in the ice cream, we can use the formula for combination.

Our variables are:
n = 31
k = 2




The number of possible combinations of having 2 different flavors out of 31 different flavors is 465.
Answer:
x = -2, 1/2
Step-by-step explanation:
Step 1: Isolate everything to 1 side
2x² + 3x - 2 = 0
Step 2: Factor
(2x - 1)(x + 2) = 0
Step 3: Find roots
2x - 1 = 0
2x = 1
x = 1/2
x + 2 = 0
x = -2
The formula for the triangular sequence is Xn=n(n+1)/2
So X25=25(25+1)/2=325