find the slope and the y-intercept

f(x) = -4x-9

The slope is
the y-intercept is (0, and ?)

All staight line equations are in the form

y=mx+c where m is the gradient and c is the intercept (0,c).

So compare your function with the general equation for a straight line and by inspection you can find m and c.

I get (0,-13)

How did you get that? Say the equation is y=-4x+9

In the form
y=mx+c it is
y=(-4)x+(-9)

so what is m and what is c?

To find the slope and y-intercept of the equation f(x) = -4x-9, we can compare it to the standard form of a linear equation, y = mx + b, where m represents the slope and b represents the y-intercept.

In the given equation, f(x) = -4x-9, we can see that the coefficient of x is -4, which is equivalent to the slope (m) of the equation.

Therefore, the slope of the equation f(x) = -4x-9 is -4.

To find the y-intercept, we need to determine the value of y when x is equal to 0.

Substituting x = 0 into the equation f(x) = -4x-9:

f(0) = -4(0) - 9
f(0) = 0 - 9
f(0) = -9

So, when x = 0, y = -9.

Therefore, the y-intercept is (0, -9).