The "slope-intercept" form of a straight line is:

y = mx + b

where m is the slope and b is the y intercept.

In our case m = -9 thus the equation is:

y = -9x + b

Next, we are going to find b.

We know the line goes through (-9, 2) meaning when x = - 9 we have y = 2 or:

(-9)*(-9) + b = 2

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click here to see the equation solved for b

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b = -79

The equation of the straight line in slope-intercept form is:

y = -9x - 79