Question

Найди значение выражений, при 3a+6b=2​

Answer 1

$\ \displaystyle\bf\\3a+6b=2\\\\1) \ \displaystyle\bf\\\dfrac{4}{a+2b} =\dfrac{4\cdot3}{(a+2b)\cdot3} =\dfrac{12}{3a+6b} =\dfrac{12}{2} =6\\\\2) \ \displaystyle\bf\\\frac{15a^{2}-60b^{2}}{5a-10b} =\dfrac{15(a^{2} -4b^{2}) }{5(a-2b)}=\dfrac{3(a-2b)(a+2b)}{a-2b} =3(a+2b)=\\\\=3a+6b=2$