Question 140807
-5x-7y=-1 ---------------------eq1
2x+9y=-12----------------------eq2


multiply each term in eq1 by 2 and each term in eq2 by 5, then add the two equations:

-10x-14y=-2--------------------------eq1a
10x+45y=-60------------------------------eq2a

adding the two equations, we get:

31y=-62  divide both sides by 31

y=-2---------------------------------------y value

substitute y=-2 into eq2

2x+9(-2)=-12
2x-18=-12  add 18 to each sid

2x-18+18=-12+18  collect like terms

2x=6  divide each side by 2

x=3-----------------------------------x value

CK
substitute the x and y values into eq1:
(-5)(3)-(7)(-2)=-1

-15+14=-1
-1=-1
substitute the x and y values into eq2:

2(3)+9(-2)=-12
6-18=-12
-12=-12



Hope this helps---ptaylor