Question

Решите пожалуйста, срочно.

Answer 1

Объяснение:

$\frac{4a^2-1}{a^2-9}:\frac{6a+3}{a+3} =\frac{(2a)^2-1}{(a+3)(a-3)} :\frac{3*(2a+1)}{a+3}=\frac{(2a+1)(2a-1)}{(a+3)(a-3)} *\frac{a+3}{3*(2a+1)}=\frac{2a-1}{3*(a-3)}.$

$\left \{ {{5x+8y=-1} \atop {x+2y=4}} \right. \ \ \ \ \left \{ {{5*(4-2y)+8y=-1} \atop {x=4-2y}} \right. \ \ \ \ \left \{ {{20-10y+8y=-1} \atop {x=4-2y}} \right. \ \ \ \ \ \left \{ {{-2y=-21\ |:2} \atop {x=4-2y}} \right. \ \ \ \ \left \{ {{y=10,5} \atop {x=-17}} \right. .$

$(\sqrt{5}-\sqrt{3})^2-\sqrt{60} =5-2*\sqrt{5}*\sqrt{3}+3 -\sqrt{4*15} = 8-2\sqrt{15} -2\sqrt{15}=8-4\sqrt{15}.$