'x + y' and 'y + x' are equivalent.
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'x - y' and 'y - x' are not equivalent.
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'x - y' and 'x-y' are equivalent.
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'x * (y + z)' and 'x*y + x*z' are equivalent.
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'x * (y + z)' and 'z * x + y * x' are equivalent.
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'x / (y + z)' and 'x/y + x/z' are not equivalent.
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'(x + y) * (x + y)' and 'x^2 + 2*x*y + y^2' are equivalent.
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'(x + y) * (x - y)' and 'x^2 + y^2' are not equivalent.
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'(x + y) * (x - y)' and 'x^2 - y^2' are equivalent.