( 5/3√7 - 4/√63 + 8/√28 ) ÷ ( - 2/3√7 )=
=(5/3√7 - 4/3√7 + 8/2√7 ) ÷ ( - 2/3√7 )=
=(1/3√7 + 4/√7 ) ÷ ( - 2/3√7 )=
=(1+12)/3√7 ÷ ( - 3√7/2 )=
=-13/2
sau rationalizezi numitorii
( 5/3√7 - 4/√63 + 8/√28 ) ÷ ( - 2/3√7 )=
=( 5/3√7 - 4/3√7 + 8/2√7 ) × ( - 3√7/2 )=
=( 1/3√7 + 4/√7 ) × ( - 3√7/2 )=
=( √7/3×7 + 4√7/7 ) × ( - 3√7/2 )=
=( √7/21 + 4√7/7 ) × ( - 3√7/2 )=
=( √7+12√7)/21 × ( - 3√7/2 )=
=( 13√7)/21 × ( - 3√7/2 )=
=-( 39×7)/(21×2)=
=-13/2