Question

I need help with finding the output y when x is -4 it's on a graph

Answer 1

As observed from the graph, the curve is a straight line from point (-2,-1) to (-5,2).

Consider that the equation of a straight line passing through two points is given by,

`y-y_1=(y_2-y_1)/(x_2-x_1)*(x-x_1)`

So the equation of the line passing through (-2,-1) and (-5,2) is given by,

`\begin{gathered} y-(-1)=(2-(-1))/(-5-(-2))*(x-(-2)) \\ y+1=(3)/(-3)*(x+2) \\ y+1=-x-2 \\ y=-x-3 \end{gathered}`

Note that this function is only for the interval [-2, -5].

Now, the value of 'y' corresponding to the input x=-4 is calculated as,

`\begin{gathered} y=-(-4)-3 \\ y=4-3 \\ y=1 \end{gathered}`

Thus, the required output is y = 1 .