Question

срочно очень надо)) (5√7-√63+√14)* √7 и вот это (√7-√12)( √7-3√3)

Answer 1

(5√7-√63+√14)*√7 =5√7*√7-√63*√7+√14*√7=35-21+7√2=21√2

Answer 2

$(5sqrt{7}-sqrt{63}+sqrt{14})* sqrt 7=\ 5sqrt{7}sqrt 7-sqrt{63}*sqrt 7+sqrt{14}* sqrt 7=\ 5*7-sqrt{63*7}+sqrt{14*7}=\ 35-sqrt{3*3*7*7}+sqrt{2*7*7}=\ 35-3*7+7sqrt{2}=\ 35-21+7sqrt{2}=\14+7sqrt{2}$

 

$(sqrt7-sqrt{12})( sqrt7-3sqrt3) =(sqrt7-2sqrt{3})( sqrt7-3sqrt3)=\ sqrt{7}sqrt{7}+sqrt{7}*(-3sqrt{7})-2sqrt{3}sqrt{7}-2sqrt{3}*(-3sqrt{7}) =\7-3sqrt{21}-2sqrt{21}+6*3=7-5sqrt{21}+18=25-5sqrt{21}$