Could some clear this up for me please? Its a bit confusing.

Find the equation of the line that is perpendicular to 4x + 7y = 13 and passes through point (-2,6). (Hint: put 4x + 7y = 13 into slope intercept FIRST.)"

http://i.imgur.com/zooBV.png

Question

Could some clear this up for me please? Its a bit confusing.

Find the equation of the line that is perpendicular to 4x + 7y = 13 and passes through point (-2,6). (Hint: put 4x + 7y = 13 into slope intercept FIRST.)"

http://i.imgur.com/zooBV.png

mathlegend · Answer

What is 4x + 7y = 13  in slope intercept form? Can you do that?

mathlegend · Answer

@Guilty404 tell me what you get?

anonymous · Answer

I am. Just trying to figure it out.

mathlegend · Answer

Show me your steps.

anonymous · Answer

Well I'm trying to figure out were to start

mathlegend · Answer

4x + 7y = 13 

We need: y = mx + b
right?

mathlegend · Answer

So lets move our 4x to other side of the equal sign. This way the problem will at least resemble y=mx+b

mathlegend · Answer

4x + 7y = 13
-4x           -4x
-------------
7y = -4x + 13

mathlegend · Answer

Do you understand that?

anonymous · Answer

Yes combining equal terms?

anonymous · Answer

or like terms

mathlegend · Answer

No, I did not combine anything. I just moved a term in this case... "4x" to the other side.

anonymous · Answer

Oh, alright. Well from the equation you posted. I can tell what you're doing.

mathlegend · Answer

Upon moving the 4x... I had to subtract .... so that minus sign had to stay with it.

mathlegend · Answer

7y = -4x + 13

Remember we want: y = mx+b
So we must solve for 'y'

mathlegend · Answer

$$\frac{ 7y= -4x+13 }{ 7 }$$How can we solve for y? It is being multiplied by 7... so we must divide both sides entirely by 7.

mathlegend · Answer

$$y=\frac{ -4 }{ 7 }x+\frac{ 13 }{ 7 }$$

mathlegend · Answer

Now, we must plug this into the point slope form equation.. since they want the equation that is perpendicular BUT also passes through (-2,6).

mathlegend · Answer

y-y1=m(x-x1)

$$y-6=\frac{ 7 }{ 4 }(x+2)$$

mathlegend · Answer

@Guilty404 do you understand everything so far?

anonymous · Answer

I am understanding it so far.

mathlegend · Answer

$$y-6=\frac{ 7 }{ 4 }x+\frac{ 7 }{ 2}$$

mathlegend · Answer

Now we add 6 to both sides...

6 + 7/2 = 19/2

mathlegend · Answer

$$y=\frac{ 7 }{ 4 }x+\frac{ 19 }{ 2 }$$

anonymous · Answer

So by adding 6 to both sides, the 6 was eliminated?

mathlegend · Answer

Yes, because it was like doing this...


y - 6 = 7x + 3
  +6             +6
-------------
y = 7x + 9

mathlegend · Answer

@Guilty404 so you understand now?

anonymous · Answer

I do*