Question

A line passes through the point

(8, 7) and has a slope of 4

Write an equation in slope-intercept form for this line.

Answer 1

y = 4x -25

Explanation:

y = 4x + b

we must find the y intercept

plug in the point

7 = 4(8) + b

7 = 32 + b

subtract 32 from both sides

-25 = b

the y intercept is -25

plug in -25 for b

y = 4x - 25

Answer 2

`(\stackrel{x_1}{8}~,~\stackrel{y_1}{7})\hspace{10em} \stackrel{slope}{m} ~=~ 4 \\\\\\ \begin{array}ll \cline{1-1} \textit{point-slope form}\\ \cline{1-1} \\ y-y_1=m(x-x_1) \\\\ \cline{1-1} \end{array}\implies y-\stackrel{y_1}{7}=\stackrel{m}{ 4}(x-\stackrel{x_1}{8}) \\\\\\ y-7=4x-32\implies {\Large \begin{array}{llll} y=4x-25 \end{array}}`