Find the point of intersection of each pair of lines, if one exists. If yo
Equation Mat, be sure to record your process on paper. Check each a
exists. If you use an
Check each solution, if
possible.
a. x=-2y-3
4y-x=9
b. x+5y=8
-x+2y=-1
c.4x - 2y = 5
y= 2x +10

there are lots of ways.   pick's theorem tells us if the vertices are lattice points the area a is

a = b/2 + i - 1

where b is the number of boundary lattice points and i is the number of interior lattice points.

in the figure i count b=16, i=50 so

a = 8 + 50 - 1 = 57

let's try the shoelace formula.   the area is half the sum of the cross products of the sides.  

a(-2,6)   -2(2)-6(-5) = 26

b(-5,2)   -5(-3) - 2(-2) = 19

c(-2,-3) -2(-3) - (-3)(4) = 18

d(4,-3)   4(3) - (-3)(5) = 27

e(5,3)   5(3) - 3(1) = 12

f(1,3)     1(6) - 3(-2) = 12

a(-2,6)

each of the cross products is twice the area of the triangle with the associated side and one vertex the origin. so the area of abo=26/2=13.

area = (1/2) (26 + 19 +   18 + 27 + 12 + 12) = 57

that checks!

yes. we do proportions in probabilities.

the answer is y < -3 or   y > 3

-3y > 7 + 2

-3 y > 9

y < -3