If x + y = 15 and xy = 14, then the value of x — y is:
Given, $$x+y\ =15$$ and $$xy=14$$
$$=$$> $$\left(x+y\right)^2=15^2$$
$$=$$> $$x^2+y^2+2xy=225$$
$$=$$> $$x^2+y^2+2xy-2xy+2xy=225$$
$$=$$> $$x^2+y^2-2xy+4xy=225$$
$$=$$> $$\left(x-y\right)^2+4\left(14\right)=225$$
$$=$$> $$\left(x-y\right)^2+=225-56$$
$$=$$> $$\left(x-y\right)^2+=169$$
$$=$$> $$x-y=13$$
Hence, the correct answer is Option A
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