20.Factorise : 81s4 – 625 – InterviewSolution

1.	20.Factorise : 81s4 – 625
Answer» TO FACTORIZE $81s {}^{4} - 625$ WE KNOW $a {}^{2} - b {}^{2} = (a + b)(a - b)$ USING this we can write above EXPRESSION as $(9s {}^{2}) {}^{2} - (25) {}^{2}$ FURTHER ,,,,,,,,,,, $it \: is \: equal \: to \: \\ \\ (9s {}^{2} + 25)(9s {}^{2} - 25)$ again we can write $9s {}^{2} - 25 \\ as \: \: (3s) {}^{2} - (5) {}^{2} \\and \: it \: can \: be \: written \: as \: \\ (3s - 5)(3s + 5)$ using the same formula ... THEREFORE THE ANSWER IS $= (9s {}^{2} + 25)(3s - 5)(3s + 5)$ THAT'S THE ANSWER ____THANK YOU____