Question

if a line crosses the y -axis at (0,-3) and has a slope of 3 , what is the equation of the line

Answer 1

y=mx+b
m=slope
b=y-intercept

Answer 2

so knowing that ^ what do you think the equation of the line is

Answer 3

\(\bf \begin{array}{lllll}
&x_1&y_1\\
% (a,b)
&({\color{red}{ 0}}\quad ,&{\color{blue}{ -3}})\quad

\end{array}
\\\quad \\
% slope = m
slope = {\color{green}{ m}}= 3
\\ \quad \\
% point-slope intercept
y-{\color{blue}{ y_1}}={\color{green}{ m}}(x-{\color{red}{ x_1}})\qquad \textit{plug in the values and solve for "y"}\\
\qquad \uparrow\\
\textit{point-slope form}\)

Answer 4

well... if you're not asked for the slope-intercept form
you don't have to solve for "y" then
just use the point-slope form