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Solve the system of equations with substitution or elimination method. please help 2x+y=4 and 6x+7y=12
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Multply both sides of the equation by 7.
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When the variable is in the numerator of a proportion like this, you can solve it by multiplying by that denominator. That multiplication cancels the denominator and gives you the value of the variable.
In general, you multiply by the reciprocal of the coefficient of x. When that coefficient is 1/7, you multiply by 7/1. Of course, you know that 7/7 = 1 and that x/1 = x.
You can find counterexamples to disprove this claim. We have positive integers that are perfect square numbers; when we take the square root of those numbers, we get an integer.
For example, the square root of 1 is 1, which is an integer. So if y = 1, then the denominator becomes an integer and thus we get a quotient of two integers (since x is also defined to be an integer), the definition of a rational number.
Example: x = 2, y = 1 ends up with which is rational. This goes against the claim that
is always irrational for positive integers x and y.
Any integer y that is a perfect square will work to disprove this claim, e.g. y = 1, y = 4, y= 9, y = 16. So it is not always irrational.