If-x-y-1-2-which-of-the-following-cannot-be-xy-

Question Number 150006 by mathdanisur last updated on 08/Aug/21

If x + y = \frac{1}{2} which of the following

cannot be xy . ?

Answered by dumitrel last updated on 08/Aug/21

x y = k \Rightarrow x + \frac{k}{x} = \frac{1}{2} \Rightarrow 2 x^{2} - x + 2 k = 0 \Rightarrow △ ⩾ 0 \Rightarrow

1 - 16 k ⩾ 0 \Rightarrow k \in (- \infty; \frac{1}{16}] \Rightarrow k \notin (\frac{1}{16}; \infty)

Commented by mathdanisur last updated on 08/Aug/21

Thank You S er

Commented by mathdanisur last updated on 08/Aug/21

Ser, answer : a . \frac{1}{15} b . \frac{1}{16} c . \frac{1}{17} d . \frac{1}{18} e . \frac{1}{19}

Commented by dumitrel last updated on 08/Aug/21

a . \frac{1}{15}

Commented by mathdanisur last updated on 08/Aug/21

Cool S er, thank you

Commented by dumitrel last updated on 08/Aug/21

x + y = s; x y = p \Rightarrow p ⩽ \frac{s^{2}}{4} \Rightarrow

p ⩽ \frac{1}{16} \Rightarrow x y \neq \frac{1}{15}