Question

срочно поможыть дам 40 балов​

Answer 1

Ответ:

$5)\ \ 15r^3-25r^3x^2=4r^3(3-5x^2)\\\\6a^2-54b^2=6(a^2-9b^2)=6(a-3b)(a+3b)\\\\\\6)\ \ 2(x-5)-4(x+3)=x-43\\\\2x-10-4x-12=x-43\ \ ,\ \ \ \ -3x=-21\ \ ,\ \ x=7\\\\\\7)\ \ y=2-x\ \ ,\ \ y=-2\ \ \ \Rightarrow \ \ \ A(4;-2)\\\\\\8)\ \ \left\{\begin{array}{l}5x+3y=7\\-2x+4y=-8\end{array}\right\ \ \left\{\begin{array}{l}5x+3y=7\\-x+2y=-4\ |\cdot 5\end{array}\right\ \oplus \ \left\{\begin{array}{l}13y=-13\\x=2y+4\end{array}\right\\\\\\\left\{\begin{array}{l}y=-1\\x=2\end{array}\right\ \ \ \ Otvet:\ (2;-1)\ .$

$9)\ \ \left\{\begin{array}{l}2x+5y=37\ |\cdot (-3)\\6x+2y=46\end{array}\right\ \oplus \ \left\{\begin{array}{l}-13y=-65\\2x=37-5y\end{array}\right\ \ \left\{\begin{array}{l}y=5\\2x=12\end{array}\right\ \ \left\{\begin{array}{l}y=5\\x=6\end{array}\right\\\\\\Otvet:\ \ x=6\ ,\ y=5\ .$

х - вес слитка олова ,  у - вес слитка свинца .