How do you solve 5x + y = 9 and 10x - 7y =-18?
1 Answer
Explanation:
Take a look at your starting system of equations
#{(5x + y = 9), (10x - 7y = -18) :}#
Notice that if you multiply the first equation by
This will leave you with one equation with one unknown,
#{(5x + y = 9 | * (-2)), (10x - 7y = -18) :}#
#{(-10x -2y = -18), (10x - 7y = -18) :}#
#stackrel("---------------------------------------------------")#
#-color(red)(cancel(color(black)(10x))) - 2y + color(red)(cancel(color(black)(10x))) - 7y = -18 + (-18)#
#-9y = -36 implies y = ((-36))/((-9)) = color(green)(4)#
Now use this value of
#5x + (4) = 9#
#5x = 5 implies x = 5/5 = color(green)(1)#