you need to find how much the output changes for each unit change in the input. (ie from an input change from 5 to 6 the output changes by three units and an input change of 3 (2 - 5 ) units the output changes by 9 units). This will give you the gradient of the equation. then you have to find out the y intercept by finding what the output is when the input is 0. Do this by multiplying the input by the gradient and then subtracting it from that inputs output. This will give you the answer A) 3x
(Sorry, its a bit wordy :) )
Given:
The given sum is:

To find:
The expanded form and find the sum.
Solution:
We have,

The expanded form of given sum is:




Therefore, the correct option is C.
Well we know that the 9.0 meter ladder is the hypotenuse And it is a right triangle with base of 1.5 meters. we have the adjacent and the hypotenuse. which is cosine. So:
cos (a) = adjacent/hypotenuse
cos (a) = 1.5/9.0
cos (a) = 1 / 6
a = cos^-1 (1 / 6)
a = 80.4 degrees
3x+3=9
x=2
that way the answer is 9