Question

(n+3) (n-3) = 40 solve quadratic equation​

Answer 1

$\tt\huge\pink{SOLUTION}$

$(n + 3)(n - 3) = 40$

Recall the Algebraic Identities,

We Know that,

$({a}^{2} ) - ( {b}^{2} ) = (a + b)(a - b)$

So,

We can write (n+3)(n-3) as

${n}^{2} - {3}^{2}$

So,

${n}^{2} - {3}^{2} = 40 \\ {n}^{2} - 9 = 40 \\ {n}^{2} = 40 + 9 \\ {n}^{2} = 49 \\ n \times n = 7 \times 7 \\ n = 7$