Question

If the points (–2, 2), (–4, 4), (2, –2), and (4, –4) are joined to form a straight line, at what point does the line intersect the y-axis?
A. (0, 0)
B. (4, –4)
C. (2, 0)
D. (0, –2)

Answer 1

well the easiest way is to make a equation:
y=mx+b , where m is slope and is y-intercept
first we need to find slope:
the slope formula is \[\frac{ y_1-y_2 }{ x_1-x_2 }\]
now substitute 2 of your points: \[\frac{ 2-4 }{ -2+4 }=\frac{ -2 }{ 2 }=-1\]
so the slope is -1. m=-1.
y=-x+b
Now substitute one of your coordinates into the equation;
(-2, 2)
2=-(-2)+b
b=2-2
b=0

b=0, b is y-intercept, thus the y-intercept is 0.

Answer 2

here are the steps for you in example of how to find an equation of any line:

Steps for finding the equation in example.
For example, write an equation of line with points (1, 3) and (-8, 6)
y=mx+b, where m is slope and b is y-intercept.
First of all we need to find slope (m). To find it, we need to use the slope formula:
\[\frac{ y_1-y_2 }{ x_1-x_2 } ~~ or~~ \frac{ y_2-y_1 }{ x_2-x_1 }\]

Substitute our points:
\[\frac{ 3-6 }{ 1+8 }=\frac{ -3 }{ 9 }=-\frac{ 1 }{ 3 }\].

Thus our slope is -1/3. Now we have that m=-1/3.
Substitute:
y=-1/3x+b.
Now we need to find the y-intercept of out equation. To do this we need to substitute one of our points into the equation and solve:
3=-1/3*1+b
b=3+1/3=10/3

Thus our equation is \[y=-\frac{ 1 }{ 3 }x+\frac{ 10 }{ 3 }\].

Answer 3

Wow youre awesome. Thank you so much...=.)