Question

If x + y = 8, x² + y2 = 4, then xy is
8​

Answer 1

Answer:

xy = 30

Step-by-step explanation:

This is ur answer.

Hope this helps u.

Answer 2

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Value\:of\:xy=30}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline \bold{Given :}} \\ \tt: \implies x + y = 8 \\ \\ \tt: \implies {x}^{2} + {y}^{2} =4 \\ \\ \red{\underline \bold{To \: Find :}} \\ \tt: \implies xy =?$

• According to given question :

$\bold{As \: we \: know \: that} \\ \tt: \implies {x}^{2} + {y}^{2} = {(x + y)}^{2} - 2xy \\ \\ \tt: \implies 4 = {8}^{2} - 2xy \\ \\ \tt: \implies 4 = 64 - 2xy \\ \\ \tt: \implies 4 - 64 = - 2xy \\ \\ \tt: \implies - 60 = - 2xy \\ \\ \tt: \implies xy = \frac{ - 60}{ - 2} \\ \\ \green{\tt: \implies xy = 30} \\ \\ \green{\tt \therefore Value \: of \: xy \: is \: 30} \\ \\ \blue{ \boxed{ \bold{Some \: related \: formula}}} \\ \orange{\tt \circ \: \: {(a + b)}^{2} = {a}^{2} + {b}^{2} + 2ab} \\ \\ \orange{\tt \circ \: \: {(a - b)}^{2} = {a}^{2} + {b}^{2} - 2ab} \\ \\ \orange{\tt \circ \: \: a^{2} + {b}^{2} = {(a - b)}^{2} + 2ab} \\ \\ \orange{\tt \circ \: \: {a}^{2} - {b}^{2} = (a + b)(a - b)} \\ \\ \orange{\tt \circ \: \: {(a + b)}^{3} = {a}^{3} + {b}^{3} + 3{a}^{2} b + {3ab}^{2} } \\ \\ \orange{\tt \circ \: \: {(a - b)}^{3} = {a}^{3} - {b}^{3} - 3{a}^{2} b + {3ab}^{2} }$