Question

If f(x) is a linear function, f(−2)=4, and f(1)=−1, find an equation for f(x)

Answer 1

Answer:

$y = -\frac{5}{3}x+\frac{2}{3}$

Step-by-step explanation:

Given

$f(-2) = 4$

$f(1) = -1$

Required

The equation of the function

The given parameters means that:

$(x_1,y_1) = (-2,4)$

$(x_2,y_2) = (1,-1)$

Calculate the slope (m)

$m = \frac{y_2 -y_1}{x_2 -x_1}$

$m = \frac{-1-4}{1--2}$

$m = \frac{-5}{3}$

The equation is then calculated using:

$y = m(x - x_1) + y_1$

This gives:

$y =\frac{-5}{3}(x--2)+4$

$y =\frac{-5}{3}(x+2)+4$

Open bracket

$y = -\frac{5}{3}x-\frac{10}{3}+4$

Take LCM

$y = -\frac{5}{3}x+\frac{-10+12}{3}$

$y = -\frac{5}{3}x+\frac{2}{3}$