Question

F(x)=5x+40 what is f(x) when x=-5?

Answer 1

`f(-5)=5\cdot(-5)+40=-25+40=15`

Answer 2

`f(-5)=15`

Explanation:

We have a linear equation:

`y=ax+b`

Where:

`a=Slope\\b=intercept\hspace{3}with\hspace{3}the\hspace{3}y\hspace{3}axis`

So:

f(x)=5x+40

Represents a straight line with a slope equal to 5 and intercept with the y-axis at 40.

Now, evaluating the function at x=-5

`f(-5)=(5)*(-5)+40=-25+40=15`