Question

Помоги плиз. Если можно, то всё.

Answer 1

$1) frac{6}{x^2+3x}- frac{2}{x}= frac{6-2x-6}{x(x+3)}=- frac{2x}{x(x+3)}=- frac{2}{x+3}$
$frac{5b}{a^2-ab}* frac{a^2-b^2}{10b^2}= frac{(a-b)(a+b)}{a(a-b)*2} = frac{a+b}{2a}$
$2) frac{x+1}{5}+ frac{x-1}{4}=1 \ frac{4(x+1)+5(x-1)-20}{20}=0 \ 4x+4+5x-5-20=0 \ 9x=21 \ x= frac{21}{9}=2 frac{1}{3}$
$3) (2.3+10^9)(3*10^{-12})= frac{2.3+10^9*3}{10^{12}} = frac{6.9*10^9}{10^{12}} = frac{6.9}{10^3}=0.0069 textgreater 0.006$
$4) 3 sqrt{2}* frac{1}{2} sqrt{8}= sqrt{18} * sqrt{ frac{8}{4} } = sqrt{ frac{18*8}{4} } = sqrt{36}=6$
$5) frac{16^{-2}*27^{-4}}{6^{-12}}= frac{6^{12}}{16^2*27^4}= frac{2^{12}*3^{12}}{2^2*2^2*2^2*2^2*3^4*3^4*3^4}=2^4=16$
$6) sqrt{45-20 sqrt{5} }= sqrt{25+20-20 sqrt{5} }= sqrt{5^2-20 sqrt{5}+20 } = \ sqrt{(5-2 sqrt{5})^2} =5-2 sqrt{5}$
др.листик
$3) frac{a^3*a^{-12}}{a^{-6}}= frac{a^3*a^6}{a^{12}} = frac{1}{a^3} \ 1:( frac{1}{2})^3=1*2^3=8$
$4) 2 sqrt{3} textgreater sqrt{11} \ sqrt{12} textgreater sqrt{11}$
$5) 23*10^{-5}= frac{23}{10^5} \ 2.7*10^{-6}= frac{2.7}{10^6}= frac{0.27}{10^5} \ 210*10^{-6}= frac{210}{10^6}= frac{21}{10^5} \ 2.7*10^{-6}; 210*10^{-6}; 23*10^{-5}$