Respuesta :
Answer: 2x-y=4 if you're looking for y then y=4/-1 or -4.0000 and x= 4/2 or 2
3x+y=21: if you're looking for y then y=21/1 in decimal form 21.00000
x= 21/3 or 7
slope=6.000/2.000 or -3.000
Step-by-step explanation: 3x+y-21 = 0
we have here an equation of a straight line. Such an equation is usually written y=mx+b ("y=mx+c".
"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 3x+y-21 = 0 and calculate its properties
Graph of a Straight Line :
Calculate the Y-Intercept :
Notice that when x = 0 the value of y is 21/1 so this line "cuts" the y axis at y=21.00000
y-intercept = 21/1 = 21.00000
Calculate the X-Intercept :
When y = 0 the value of x is 7/1 Our line therefore "cuts" the x axis at x= 7.00000
x-intercept = 21/3 = 7
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 21.000 and for x=2.000, the value of y is 15.000. So, for a change of 2.000 in x (The change in x is sometimes referred to as "RUN") we get a change of 15.000 - 21.000 = -6.000 in y. (The change in y is sometimes referred to as "RISE" and the Slope is m = RISE / RUN)
Slope = -6.000/2.000 = -3.000
Slope = -6.000/2.000 = -3.000
x-intercept = 21/3 = 7
y-intercept = 21/1 = 21.00000