Got you. So we will use the basic formula for the area of a rectangle and insert variable values. (^_^)
Area= Width(Height) ----------- Insert values of width and height [width = (x-1)
, height = (x+9)]
Area= (x-1)(x+9) ) -------------- Then expand if needed?
= x² +8x -9
X = 0 ; y = 10 ; 10 = a(0) + b(0) + c
c = 10
x=2 ; y = 15 ; 15 = a(4) + b(2) + 10 ; 5 = 4a+2b
x=4 ; y=18 ; 18 = a(16) + b(4) + 10 ; 8 = 16a + 4b
2(5) = (4a+2b)2
-
<u> 8 = 16a + 4b
</u> 2 = -8a
a = -0.25
b = 2
y = (1/4)x^2 + 2x + 10 ; 4y = x^2 + 8x + 40
