Step-by-step explanation:
(7/9a+9/7b)^2 -ab
simplifying (7/9a+9/7b)^2
expanding the bracket
[tex] = ( \frac{7}{9a} + \frac{7}{7b} ) \: ( \frac{7}{9a} + \frac{7}{7b} ) - ab[/tex]
[tex] = \frac{49}{81 {a}^{2} } + \frac{49}{63ab} + \frac{49}{63ab} + \frac{49}{49 {b}^{2} } - ab[/tex]
[tex] = \frac{49}{81 {a}^{2} } + \frac{98}{63ab} + {b}^{2} - ab[/tex]
factorizing b out
49/81a^2 +98/63ab +b(b-a)
the l.c.m= (81a^2) (63ab)
multiplying through by the L.C.M
63ab×49 +98×81a^2 +b(b-a) ×81a^2 ×63ab
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