Find rates of change until you find a constant.
dy/dx=1,2,3,4,5,6
d2y/dx2=1,1,1,1,1
So the acceleration, d2y/d2x, is constant. This means that this is a quadratic sequence of the form a(n)=an^2+bn+c. So we can set up a system of equations to solve for the values of a,b, and c. Using the first three points, (1,1), (2,2), and (3,4) we have:
9a+3b+c=4, 4a+2b+c=2, and a+b+c=1 getting the differences...
5a+b=2 and 3a+b=1 and getting this difference...
2a=1, so a=1/2 making 5a+b=2 become:
2.5+b=2, so b=-1/2, making a+b+c=1 become:
1/2-1/2+c=1, so c=1 so the rule is:
a(n)=0.5x^2-0.5x+1 or if you prefer to not have decimals
a(n)=(x^2-x+2)/2
Answer:
see explanation
Step-by-step explanation:
the perimeter (P) is the sum of the 4 sides
(a)
P = a + b + c + d
= x + 7 + 2x + 2 + 8x + x + 10 ← collect like terms
= 12x + 19
(b)
If x = 4 , then
P = 12x + 19 = 12(4) + 19 = 48 + 19 = 67
(c)
If x = 2 , then
P = 12x + 19 = 12(2) + 19 = 24 + 19 = 43
(d)
P = a + b + c + d
= x² + 4x + 8 + 2x² + x ← collect like terms
= 3x² + 5x + 8
