SOLUTION: Give a counterexample to show that (x+y)2 = x2 + y2 is false.

Question 737616: Give a counterexample to show that (x+y)2 = x2 + y2 is false.
Found 2 solutions by richwmiller, MathLover1:
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
let x=1 y=2
(1+2)^2=1^2+2^2
3^2=1+4
9=5
not true

Answer by MathLover1(20850) (Show Source): You can put this solution on YOUR website!

To find a counter example to " is ", you must use and so that .
Presumably you know that . That means you must find and so that .
...notice that the squares on both sides cancel
What does that leave you with?
...this is true only if only or , or both and
so, it proves that

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