Question

Ajutatima !!!!
$(3 \sqrt{5}-2)(3 \sqrt{5} -1)$
$(2 \sqrt{8} +3 \sqrt{5} -7 \sqrt{2} )( \sqrt{72}+ \sqrt{20}-4 \sqrt{2} )$

Answer 1

a) ( 3√5-2)(3√5-1)= 45-3√5-6√5+2= 47-9√5; b) (2√8+3√5-7√2)(√72+√20-4√2)= (2√8+3√5-7√2)(3√8+2√5-4√2)= 48+4√40-8√16+9√40+30-12√10-21√16-14√10+56=134+13√40-116-26√10= 13√40-26√10+18= 13(√40-2√10)+ 18= 13(2√10-2√10)+18= 13*0+18= 0+18= 18

Answer 2

$a).(3 \sqrt{5} -2)(3 \sqrt{5} -1)=45-3 \sqrt{5} -6 \sqrt{5} +2=47-9 \sqrt{5} \\ b).(2 \sqrt{8} +3 \sqrt{5} -7 \sqrt{2} )( \sqrt{72} + \sqrt{20} -4 \sqrt{2} )= \\ =(2 \sqrt{8} +3 \sqrt{5} -7 \sqrt{2} )(6 \sqrt{2} +2 \sqrt{5} -4 \sqrt{2} )= \\ =12 \sqrt{16} +4 \sqrt{40} -8 \sqrt{16} +18 \sqrt{10} +30-12 \sqrt{10} -84-14 \sqrt{10} +56= \\ =48+8 \sqrt{10} -32+18 \sqrt{10} +30-12 \sqrt{10} -84-14 \sqrt{10} +56= 18$