### Home > AC > Chapter 12 > Lesson 12.4.3 > Problem 12-94

12-94.

If

*f*(−1) = 7 and*f*(3) = 8, and if the graph of*f*(*x*) is a line: Homework Help ✎Graph the line on graph paper.

Find the equation for

*f*(*x*).If

*g*(*x*) is a line that is perpendicular to*f*(*x*), what is its slope?

*f*(−1) = 7 represents the point (−1, 7).

Graph this point and the point corresponding to *f*(3) = 8 in order to sketch the line.

Use the *y* = m*x* + b format wherem = slope (growth) and b = *y*-intercept (starting point).

Find the growth and substitute one of the coordinates of a point in the problem and solve for b.

A line *g*(*x*) that is perpendicular to *f*(*x*) has a slope that is the negative reciprocal of the slope of the line *f*(*x*).