Question

How do you use subsitution for5x+2y=4

Answer 1

Rearrange:

Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :

                    5*x+2*y-(4)=0

Equation of a Straight Line

1.1     Solve   5x+2y-4  = 0

Tiger recognizes that we have here an equation of a straight line. Such an equation is usually written y=mx+b ("y=mx+c" in the UK).

"y=mx+b" is the formula of a straight line drawn on Cartesian coordinate system in which "y" is the vertical axis and "x" the horizontal axis.

In this formula :

y tells us how far up the line goes

x tells us how far along

m is the Slope or Gradient i.e. how steep the line is

b is the Y-intercept i.e. where the line crosses the Y axis

The X and Y intercepts and the Slope are called the line properties. We shall now graph the line  5x+2y-4  = 0 and calculate its properties

Graph of a Straight Line :

Calculate the Y-Intercept :

Notice that when x = 0 the value of y is 2/1 so this line "cuts" the y axis at y= 2.00000

 y-intercept = 4/2  =  2  

Calculate the X-Intercept :

When y = 0 the value of x is 4/5 Our line therefore "cuts" the x axis at x= 0.80000

 x-intercept = 4/5  =  0.80000  

Calculate the Slope :

Slope is defined as the change in y divided by the change in x. We note that for x=0, the value of y is 2.000 and for x=2.000, the value of y is -3.000. So, for a change of 2.000 in x (The change in x is sometimes referred to as "RUN") we get a change of -3.000 - 2.000 = -5.000 in y. (The change in y is sometimes referred to as "RISE" and the Slope is m = RISE / RUN)

   Slope     = -5.000/2.000 = -2.500  

Geometric figure: Straight Line

 Slope = -5.000/2.000 = -2.500

 x-intercept = 4/5 = 0.80000

 y-intercept = 4/2 = 2