The coordinates below represent two linear equations.

how many solutions does this system of equations have?

line 1
x y
–4 5
0 2
line 2
x y
0 5
4 2

a.
0

b.
exactly 1

c.
exactly 2

d.
infinitely many

So solve for the equations of the lines
y=mx+b
m=slope
b=y intercept

line 1=
(-4,5)
(0,2)
(x,y)
slope=(y1-y2)/(x1-x2)
x1=-4
y1=5
x2=0
y2=2
subsitute
(5-2)/(-4-0)=3/-4=-3/4
slope=-3/4
subsitute
y=-3/4x+b
subsitute one of the points
(0,2)
x=0 and y=2 is one solution
2=-3/4(0)+b
2=0+b
2=b
the equation is y=-3/4x+2

other line
(0,5)
(4,2)
x1=0
y1=5
x2=4
y2=2
sybsitute
(5-2)/(0-4)=3/-4=-3/4
slope=-3/4
subsitute
y=-3/4x+b
now subsitute one of the points to solve for b
(0,5)
x=0 and y=5 is one solution
5=-3/4(0)+b
5=0+b
5=b
y=-3/4x+5

so we have the lines/equations
y=-3/4x+2 and y=-3/4x+5
(at this point we can see that since slopes are the same and the y intercepts are different, they are paralell and therefor have 0 solutions, but for those who don't know paralellline thingie read on)

solve for  common (x,y)
y=-3/4x+2
y=-3/4x+5
subsitute
-3/4x+2=y=-3/4x+5
-3/4x+2=-3/4x+5
subtract 2 from both sides
-3/4x=-3/4x+5
add 3/4x to both sides
0=5
fasle
there are no solutions

the answer is A: 0 solutions

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