Solve this by using suitable identities
(3a+4)? - (3a-4)?

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Solution

Question should be (3a + 4)² -(3a - 4)²
=(9a²+16+24a) -(9a²+16-24a) [(a+b) ² = a²+b²+2ab ]
=9a²+16+24a -9a²-16+24a
=48a

Alternate way :
(3a + 4)² -(3a - 4)² [a² - b² = (a+b)(a-b)]
((3a+4) +(3a-4))((3a+4)-(3a-4))
=(6a)(8)
=48a

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