Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2012-08-05 21:30:52

ac88218
Member
Registered: 2012-08-05
Posts: 3

point-gradient form of a linear equation

hello,
Just wondering if anyone can help me out with this question my teacher set me, thanks
"Find the equation of a line with a gradient of -4 and an x-intercept of 5"
hope someone can help...

Offline

#2 2012-08-05 21:35:24

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,268

Re: point-gradient form of a linear equation

hi ac88218

just typing this up.  Stay on-line if you can.

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

Offline

#3 2012-08-05 21:36:26

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,268

Re: point-gradient form of a linear equation

The point gradient form looks like this:


You are told that m = -4 and that (5,0) is one point.  So

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

Offline

#4 2012-08-05 21:39:48

ac88218
Member
Registered: 2012-08-05
Posts: 3

Re: point-gradient form of a linear equation

Thanks,
I know the formula, I think I need to know how to find the y-intercept to keep going from here because I know how to do it with both intercepts,
if you could help me find out how that would be great

Offline

#5 2012-08-05 21:52:45

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,268

Re: point-gradient form of a linear equation

OK.

I did add some more to post 3 but I'll show you how to get the y intercept without knowing that equation.

As the gradient is minus 4, that will mean for every 1 you step left in the x direction, the y coordinate will go up by  4. 

So step back a few points like this:

(5,0)  ... (4,4) ... (3,8) ... (2,12) ... (1,16) ... (0,20)

So the y intercept is (0,20)

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

Offline

#6 2012-08-05 21:56:54

ac88218
Member
Registered: 2012-08-05
Posts: 3

Re: point-gradient form of a linear equation

thanks so much, didn't realise it was that easy

Offline

Board footer

Powered by FluxBB