a = ( √2 + √50 - √72 ) · √5 - 16/21 : ( - 2/63 )
a = ( √2 + 5√2 -6√2 ) · √5 - 16/21 · ( - 63/2 )
a = ( 6√2 - 6√2 ) · √5 + 24/1
a = 0 · √5 + 24
a = 0 + 24
a = 24 ∈ N
*!! -16/21 · ( -63/2) se simplifica. Minus · minus = plus, 16 simplificat cu 2 ramane 8, 63 simplificat cu 21 ramane 3. (8·3 = 24)
