"The function y= f(x) is linear. The line y= 14 intersects the graph of y= |f(x)| at (6, 14) and (-8, 14). The line y= 6 intersects the graph of y= |f(x)| at (2,6) and (-4,6). What is an equation for the function of y= f(x)?"

Question

anonymous · Answer

we can see that

either f(6) = 14 , f(-8) = -14

or f(6) = -14 , f(-8) = 14

anonymous · Answer

either way we can work out the magnitude of the gradient

anonymous · Answer

let f(x) = mx + c

$$m = \pm \frac{14 - (-14)}{6-(-8)} = \pm \frac{28}{14} = \pm 2$$

anonymous · Answer

OH MY GOSH. Uhm, the answer is supposed to be just 2x+2. We've never used this formula before.

anonymous · Answer

hang on maybe i'm overcomplicating

anonymous · Answer

could it not be also

y =  -2x - 2

anonymous · Answer

thank you though. Haha. yeah it can be that too, I just dont know how to solve this. D':