How do you write an equation of a line with slope of 3 and contains the point (4, 9)?

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How do you write an equation of a line with slope of 3 and contains the point (4, 9)?

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Answer 1 · 2018-03-22T19:03:46

$y = 3 x - 3$ $y=3x-3$

Explanation:

$the equation of a line in slope-intercept form$ $"the equation of a line in "color(blue)"slope-intercept form"$ is.

$∙ x y = m x + b$ $•color(white)(x)y=mx+b$

$where m is the slope and b the y-intercept$ $"where m is the slope and b the y-intercept"$

$here m = 3$ $"here "m=3$

$\Rightarrow y = 3 x + b \leftarrow is the partial equation$ $rArry=3x+blarrcolor(blue)"is the partial equation"$

$to find b substitute (4, 9) into the partial equation$ $"to find b substitute "(4,9)" into the partial equation"$

$9 = 12 + b \Rightarrow b = 9 - 12 = - 3$ $9=12+brArrb=9-12=-3$

$\Rightarrow y = 3 x - 3 \leftarrow is the equation of the line$ $rArry=3x-3larrcolor(red)"is the equation of the line"$

Answer 2 · 2018-03-22T19:15:02

$y = 3 x - 3$ $y = 3x-3$

Explanation:

You can use the equation of a line in point-slope form:
$y - y_{1} = m (x - x_{1})$ $y-y_{1} = m(x-x_{1})$

Make the following substitutions:
$x_{1} = 4$ $x_{1} = 4$ (the x-coordinate of the point)
$y_{1} = 9$ $y_{1} = 9$ (the y-coordinate of the same point)
$m = 3$ $m = 3$ (the slope of the line)

That will give you:
$y - 9 = 3 (x - 4)$ $y-9 = 3(x-4)$

Then simplify:
$y - 9 = 3 (x - 4)$ $y-9 = 3(x-4)$
$y - 9 = 3 x - 12$ $y-9 = 3x-12$
$y = 3 x - 3$ $y = 3x-3$

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How do you write an equation of a line with slope of 3 and contains the point (4, 9)?

2 Answers

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