(2 akar 3-6 akar 7) (4 akar 5+ akar 7)

(2√3 – 6√7)(4√5 + √7)
= 2√3 . 4√5 + 2√3 . √7 + (-6√7).4√5 +
(-6√7).√7

= 8√15 + 2√21 – 24√35 – 6√49

= 8√15 + 2√21 – 24√35 – 6.7

= 8√15 + 2√21 – 24√35 – 42