Because 3 is a lower number then 5 and that would be negative if it were 5+3 it would be Positive
If one side is 3 inches, the perimeter would be 5x3 which is 15. In terms of algebra, if one side is y, then the perimeter is 5y.
The percent of decrease from 100 to 49 is -51%
Step-by-step explanation:
1. The first step has 1 block. The second step has 2 blocks. The third step has 3 blocks. So the nth step needs n blocks.
2. A staircase with n steps has 1 + 2 + 3 + ... + n steps. This is an arithmetic sequence where the first term is 1 and the last term is n. The sum of the first n terms is:
y = n/2 (1 + n)
3. Solve for n.
2y = n (1 + n)
2y = n² + n
0 = n² + n − 2y
Using quadratic formula:
n = [ -1 ± √(1 − 4(1)(-2y)) ] / 2
n = [ -1 + √(1 + 8y) ] / 2