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40 votes
40 votes
Find the equation of the line that passes through (2,-1) and is parallel to

y
=
4

2
x

I am unsure of the answer

User Sam Rao
by
3.8k points

2 Answers

14 votes
14 votes
Equation of a line passing through a point
Equation of a line passing through a point

(1,1) is given by −1=(−1)
(
x
1
,
y
1
)
is given by
y

y
1
=
m
(
x

x
1
)

where m is the slope of the line. We find the slope of the given line.
where m is the slope of the line. We find the slope of the given line.

2+−4=0⟹=−2+4⟹slop of the line = -2
2
x
+
y

4
=
0

y
=

2
x
+
4

slop of the line = -2

Since the two lines are parallel their slopes are equal
Since the two lines are parallel their slopes are equal

Equation of the line passing through (2, -1) with slope -2 is:
Equation of the line passing through (2, -1) with slope -2 is:

+1=−2(−2)
y
+
1
=

2
(
x

2
)

⟹2++1−4=0

2
x
+
y
+
1

4
=
0

⟹2+−3=0 is the required equation

2
x
+
y

3
=
0
is the required equation

1




Related questions (More answers below)
User Tdhulster
by
3.1k points
21 votes
21 votes

Hi student, let me help you out!

..................................................................................................................

----------------------------------------------

Part 1.

What is the slope of the line
\mathtt{y=4-2x}?

  • slope = -2

---------------------------------------------

Part 2.

What is the slope of the line that is parallel to the line
\mathtt{y=4-2x}?

  • slope =
    \mathtt{-2}


\dag\mathtt{Drawing\:Conclusions}

The slopes of parallel lines are identical.

----------------------------------------------------

Part 3. Equation

Now that we've found the slope, we can easily find the equation.

Recall the point that the line contains: (2, -1).

Let's stick in its y-coordinate, -1, instead of y:
\mathtt{-1=-2x+b}

Do the exact same thing with x:
\mathtt{-1=-2(2)+b}.

Upon simplifying, we obtain
\mathtt{-1=-4+b}.

Now we should add 4 to both sides:
\mathtt{-1+4=b}.

Upon simplifying, we obtain
\mathtt{3=b}

  • Incase you're wondering, "b" is the y-intercept.

∴, the equation of the line is
\underline{\boxed{\mathtt{y=-2x+3}}}.

Hope this helped you out, ask in comments if any queries arise.

Best Regards!


\star\bigstar\underline{\underline{\overline{\overline{\bold{Reach\:Far.\:Aim\:high.\:Dream\:big.}}}}}\bigstar\star


\underline{\rule{300}{3}}

User Pacemaker
by
3.1k points