If x is a real number, find 49x^2+14x(19-7x)+(19-7x)^2.
\(49x^2+14x(19-7x)+(19-7x)^2\\ =49x^2+266x-98x^2+361-266x+49x^2\\ =361\)
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x does not have to be a real number. Any real or complex number will yield the same result.
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