Question

1,2,4 Очеееень срочно

Answer 1

$1. frac{7}{3} times frac{6}{7} - frac{9}{4} times frac{4}{23} =2- frac{9}{23} =1 frac{14}{23}$

$2. sqrt{2^2+( sqrt{7})^2+2*2* sqrt{7} } - sqrt{1^2+( sqrt{3})^2-2*1* sqrt{3} } =\\= sqrt{(2+ sqrt{7})^2 }- sqrt{( sqrt{3} -1)^2} =2+ sqrt{7} - sqrt{3} +1=\\=3+ sqrt{7} - sqrt{3}$

$4.5x-9+5x-7=4\\ 10x=20\\ x=2$