Find the Function Perpendicular to y=-1/5x+3 Through Point (2,9)

Perpendicular Lines with Point-Slope Form

A line passes through the point (2,9) (2,9) and is perpendicular to the line y=15x+3 y=-\frac{1}{5}x+3 .

Choose the corresponding function.

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step video solution

Watch the teacher solve the problem with clear explanations

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

A line passes through the point (2,9) (2,9) and is perpendicular to the line y=15x+3 y=-\frac{1}{5}x+3 .

Choose the corresponding function.

2

Step-by-step solution

To solve this problem, follow these steps:

Step 1: Identify the slope of the given line.

The given line is y=15x+3 y = -\frac{1}{5}x + 3 . Here, the slope (m m ) is 15-\frac{1}{5}.

Step 2: Determine the slope of the perpendicular line.

For lines to be perpendicular, the product of their slopes must equal 1-1. Hence, if m1=15 m_1 = -\frac{1}{5} is the slope of the given line, the slope (m2 m_2 ) of the line perpendicular to it can be found using:

m1×m2=1 m_1 \times m_2 = -1 , which implies:

15×m2=1-\frac{1}{5} \times m_2 = -1.

Solve for m2 m_2 to get:

m2=5 m_2 = 5 .

Step 3: Use the point-slope form to find the equation of the line.

The line passes through point (2,9)(2, 9), and we have determined m2=5 m_2 = 5 .

Using the point-slope form yy1=m(xx1) y - y_1 = m(x - x_1) , substitute m=5 m = 5 , x1=2 x_1 = 2 , y1=9 y_1 = 9 :

y9=5(x2) y - 9 = 5(x - 2) .

Step 4: Simplify the equation.

Distribute the 5:

y9=5x10 y - 9 = 5x - 10 .

Add 9 to both sides to solve for y y :

y=5x1 y = 5x - 1 .

Therefore, the equation of the line we are looking for is y=5x1\boxed{y = 5x - 1}.

3

Final Answer

y=5x1 y=5x-1

Key Points to Remember

Essential concepts to master this topic
  • Perpendicular Rule: Slopes multiply to equal negative one
  • Technique: Negative reciprocal of 15 -\frac{1}{5} is 5 5
  • Check: Point (2,9) satisfies y=5x1 y = 5x - 1 : 9=5(2)1=9 9 = 5(2) - 1 = 9

Common Mistakes

Avoid these frequent errors
  • Using reciprocal instead of negative reciprocal for perpendicular slope
    Don't just flip 15 -\frac{1}{5} to get 5 -5 = parallel lines, not perpendicular! This gives the same direction instead of perpendicular direction. Always use the negative reciprocal: flip the fraction AND change the sign.

Practice Quiz

Test your knowledge with interactive questions

Look at the linear function represented in the diagram.

When is the function positive?

–8–8–8–7–7–7–6–6–6–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333444555666777888–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333000

FAQ

Everything you need to know about this question

How do I remember the rule for perpendicular slopes?

+

Think "negative reciprocal" - flip the fraction AND change the sign. For 15 -\frac{1}{5} , flip to get 51 -\frac{5}{1} , then change sign to get +5 +5 .

Why do perpendicular slopes multiply to equal -1?

+

This comes from geometry! When two lines are perpendicular, they form 90-degree angles. The mathematical relationship that creates this right angle is when m1×m2=1 m_1 \times m_2 = -1 .

What if the original slope is a whole number?

+

Write it as a fraction first! For example, if the slope is 3 3 , write it as 31 \frac{3}{1} . The perpendicular slope would be 13 -\frac{1}{3} .

Can I use slope-intercept form instead of point-slope form?

+

Yes! Both methods work. Point-slope form yy1=m(xx1) y - y_1 = m(x - x_1) is often easier when you have a specific point, but you can also find the y-intercept and use y=mx+b y = mx + b .

How do I check if my final answer is correct?

+

Do two checks: (1) Verify the given point satisfies your equation, and (2) multiply your slope by the original slope to get 1 -1 .

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Linear Functions questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations