Question

Factorise 80a square-9c square

Answer 1

Correction in the question :

81 a² - 9 c²

⇒ ( 9 a )² - ( 3 c )²

Using identity ;

a² - b² = ( a + b ) ( a - b )

⇒ ( 9 a + 3 c ) ( 9 a - 3 c )

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Answer 2

$\underline \bold {Solution:-}$

$80 {a}^{2} - 9 {c}^{2} \\ \\ = {( \sqrt{80} a)}^{2} - {(3c)}^{2} \\ \\ \bold {using \: identity} \\ \\ {x}^{2} - {y}^{2} = (x + y)(x - y) \\ \\ \bold {= ( \sqrt{80} a + 3c)( \sqrt{80} a - 3c)}$

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