Question

пожалуйста помогите мне)

Answer 1

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Answer 2

4) =$sqrt{ frac{(2,87-1,97)(2,87+1,97)}{(4,37-3,47)(4,37+3,47)} } = sqrt{ frac{0,9*4,84}{0,9*7,84} }= sqrt{ frac{484}{784} }= frac{22}{28}= frac{11}{14}$
№341
2) =$sqrt{( sqrt{7})^2-2*2 sqrt{7}+2^2 }= sqrt{( sqrt{7}-2)^2 }= sqrt{7}-2$
=$sqrt{( sqrt{7})^2-2*3 sqrt{7}+3^2 }= sqrt{( sqrt{7}-3)^2 } =3- sqrt{7}$
$sqrt{7}-2+3- sqrt{7} =1$
4)6-√20=6-2√5=(√5)²-2√5+1²=(√5-1)²
6+√20=6+2√5=(√5)²+2√5+1²=(√5+1)²
$frac{1}{ sqrt{5}-1+1 }- frac{1}{ sqrt{5}+1-1 } = frac{1}{ sqrt{5} }- frac{1}{ sqrt{5} }=0$