Question

EXPLAIN THE ERROR Cody was given two points (1/2,4) and (2/3,1), on a line and asked to create a linear equation in standard form. Cody’s work in shown. Identify any errors and correct them

Answer 1

Answer:

Cody made a mistake when calculating the slope of the line and this affected every other steps after than.

She divided -3 by 6 instead of -3 by 1/6

Step-by-step explanation:

Given

$(x_1,y_1) = (\frac{1}{2},4)$

$(x_2,y_2) = (\frac{2}{3},1)$

See attached for steps

Required

Explain Cody's error

Cody made a mistake when calculating the slope of the line and this affected every other steps after than.

See Proof

Slope (m) is calculated as thus:

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

$m =\frac{1 - 4}{\frac{2}{3} - \frac{1}{2}}$

$m =-\frac{ 3}{\frac{1}{6}}$

$m = -3/\frac{1}{6}$

$m = -3 * 6$

$m = -18$

This is in contrast to $m = -\frac{1}{2}$, calculated by Cody

Solving further to determine the equation.

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

Where

$(x_1,y_1) = (\frac{1}{2},4)$

$m = -18$

$y - 4 = -18(x - \frac{1}{2})$

$y - 4 = -18x + 9$

Collect Like Terms

$y + 18x = 9 + 4$

$y + 18x = 13$