Question

a rectangular plot of land measures [3x+9]m by [x-3]m and has an area of 648m^2
a) write an equation for the area of the plot in the form ax^2+bx+c=0
b) determine the dimensions of the plot.
c) another similar plot has an area of 2592m^2. find the dimensions of the plot

Answer 1

(a,b) (3x+9)(x-3) = 3(x+3)(x-3) = 3(x^2-9) = 648
x^2-9 = 216
x^2 = 225
x = 15
(c) 2592/648 = 4
so each dimension is √4=2 times as big