Question

Help!!Вы можете даже только 13 решить,но с решением!!​

Answer 1

Ответ:

Пошаговое объяснение:

1. (a+b)²=a²+b²+2ab

a-b=11 ;  ab=23;

(a-b)²=a²+b²-2ab=11²

2ab=2·23=46

a²+b²=121+46=167

(a+b)²=a²+b²+2ab=167+46=213

(a+b)²=213

2, (m-n)²=m²+n²-2mn

    m+n=13;    mn=27;

(m+n)²=m²+n²+2mn=13²;     2mn=2×27=54

m²+n²=169-2mn=169-54=115

(m-n)²=m²+n²-2mn= 115-54=61

(m-n)²=61

Answer 2

Ответ:

$13.\ \ \left\{\begin{array}{l}a-b=11\\ab=23\end{array}\right\ \ \left\{\begin{array}{l}(a-b)^2=121\\ab=23\end{array}\right\ \ \left\{\begin{array}{l}a^2+b^2-2ab=121\\ab=23\end{array}\right$

$\left\{\begin{array}{l}a^2+b^2=121+2ab\\ab=23\end{array}\right\ \ \left\{\begin{array}{l}a^2+b^2=121+2\cdot 23\\ab=23\end{array}\right\ \ \left\{\begin{array}{l}a^2+b^2=167\\ab=23\end{array}\right\\\\\\(a+b)^2=\underbrace{a^2+b^2}_{167}+2\underbrace {ab}_{23}=167+2\cdot 23=167+46=\boxed{213}$

$14.\ \ \ \left\{\begin{array}{l}m+n=13\\mn=27\end{array}\right\ \ \left\{\begin{array}{l}(m+n)^2=169\\mn=27\end{array}\right\ \ \left\{\begin{array}{l}m^2+n^2+2mn=169\\mn=27\end{array}\right$

$\left\{\begin{array}{l}m^2+n^2=169-2mn\\mn=27\end{array}\right\ \ \left\{\begin{array}{l}m^2+n^2=169-2\cdot 27\\mn=27\end{array}\right\ \ \left\{\begin{array}{l}m^2+n^2=115\\mn=27\end{array}\right\\\\\\(m-n)^2=\underbrace{m^2+n^2}_{115}-2\underbrace{mn}_{27}=115-2\cdot 27=\boxed {61}$