How do you solve the following linear system: # 3x+y=4 , 6x-y=5 #?

1 Answer
Tony B
Mar 29, 2016

#x=1#
#y=1#

Explanation:

The simplest way to start this one is to just add the equation. That way you eliminate the y and you cans solve for #x#. Once the value of #x# is determined, then by substitution, the value of #y# can be determined.

Starting point

#" "3x+y=4#
#" "underline(6x-y=5)" "->"Addition"#
#" "9x+0y=9#

#=>9x=9#

So # x=1#

By substitution of #x=1" in "3x+y=4# we have

#" "3(1)+y=4#

#" "y=4-3#

#" "y=1#

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