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Question 58365: Hi,
I can do this problem by sight; meaning I know what numbers will work by looking at it, I do not know how to do them if I couldn't do it by sight though.
The problem is:
x-2y=4
I did x=4 and y=0.
I know by looking at this that x could equal zero and y could equal a -4.
I do not know how to do the problem other than by figuring out in my head what 2 numbers would leave me with the answer of 4.
I hope you can help me. Thank you.
Answer by funmath(2933)   (Show Source):
You can put this solution on YOUR website! The problem is:
x-2y=4
It's great that you're thinking, but you're thinking too hard. Pick an easy number to deal with and substitute it into the equation and solve for the other variable. There are an infinite number of choices.
:
If x=0, then:
(0)-2y=4
-2y=4
-2y/-2=4/-2
y=-2 The ordered pair (x,y)=(0,-2)
Check: 0-2(-2)=4
4=4
:
If y=0, then:
x-2(0)=4
x-0=4
x=4 The ordered pair is (x,y)=(4,0)
Check: 4-2(0)=4
4=4
:
If x=2, then:
2-2y=4
-2+2-2y=-2+4
-2y=2
-2y/-2=2/-2
y=-1 The ordered pair is (x,y)=(2,-1)
Check: 2-2(-1)=4
2+2=4
4=4
:
You really can pick an infinite number of possibilities. A person could lose a brain cell doing that in their head!!!
Happy Calculating!!!
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