How do you find the slope for 2x + 4y = 8?

2 Answers
Apr 9, 2016

Gradient is -1/2" value corrected from "-1/4 to -1/212 value corrected from 1412

Explanation:

Given:" "color(brown)(2x+4y=8) 2x+4y=8

color(blue)("Using shortcut method")Using shortcut method

Divide both sides by 4 so that there is no number (coefficient) in front of yy

2/4x+y=2" "->" corrected from "1/4x to 2/4x24x+y=2 corrected from 14x24x

1/2x+y=212x+y=2

But the x term is on the same side as the y term so

color(blue)("gradient" = (-1)xx1/2=-1/2" "->" final value corrected"gradient=(1)×12=12 final value corrected

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(blue)("Using first principles method ")Using first principles method

Subtract color(blue)(2x)2x from both sides

" "color(brown)(2xcolor(blue)(-2x)+4y=8color(blue)(-2x)) 2x2x+4y=82x

But 2x-2x=02x2x=0 giving

" "0+4y=-2x+8 0+4y=2x+8

Divide both sides by 4

" "4/4 xx y=-2/4 x+8/4 44×y=24x+84

But 4/4 =1" and "1xx y=y44=1 and 1×y=y giving

" "x=-1/2 x+2" "->" corrected from "-1/4x" to "-1/2x x=12x+2 corrected from 14x to 12x
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Now your equation is in standard form of

y=mx+cy=mx+c where m is the gradient

color(blue)(=>m=-1/2)m=12

Apr 9, 2016

The slope (the gradient) of the function is: -1/212

Explanation:

If we rearrange the function to what is referred to as Gradient Form we can determine the slope (the gradient) of the function.

Gradient form can be defined as:

y=mx+cy=mx+c

Where mm is the gradient (the slope of the line)
and cc is the constant term of the function (effectively the y- intercept)

Therefore, if we rearrange the function you have given into Gradient Form :
2x+4y=82x+4y=8
4y=-2x+84y=2x+8
y=-2/4x+2y=24x+2
y=-1/2x+2y=12x+2
Therefore, when rearranged into Gradient Form we can see that the coefficient of mm is -1/212, therefore the gradient (slope) of the function is: -1/212