How do you find the solution set for x+9y=-1, 2x+4y=5?

1 Answer
Aug 6, 2015

Answer:

#{(x = 7/2), (y=-1/2) :}#

Explanation:

You could solve this system of equations by suing the substitution method.

To do that, use the first equation to write #x# as a function of #y#

#x + 9y = -1#

#x = -1 - 9y#

Now use this expression in the second equation - this will get you the value of #y#

#2x + 4y = 5#

#2 * (-1-9y) +4y = 5#

#-2 - 18y + 4y = 5#

#-14y = 7 implies y = 7/(-14) = color(green)(-1/2)#

FInally, use the value of #y# to get the value of #x#

#x = -1 - 9 * (-1/2)#

#x = -1 + 9/2 = color(green)(7/2)#