1.

Simplify : (6a^2-a+1)-(4-10a-3a^2)

Answer»

(6a2- a + 1) - (4 -10a - 3a2)

= 6a2- a +1 - 4 +10a +3a2

= 9a2 + 9a - 3

= 9 (a2 + a - \(\frac{1}{3}\))

= 9 (a2 + a + \(\frac{1}{4}\) - \(\frac{1}{4}\) - \(\frac{1}{3}\))

= 9 ((a + \(\frac{1}{2}\))2 - (\((\sqrt{\frac{7}{12}})^2\))

= 9 (a + \(\frac{1}{2}\) - \(\frac{\sqrt{21}}{6}\)) (a + \(\frac{1}{2}\) + \(\frac{\sqrt{21}}{6}\))

(∵ a2 - b2 = (a+b)(a-b) & \(\sqrt{\frac{7}{12}}\) = \(\frac{1}{2}\)\(\sqrt{\frac{7}{3}}\) = \(\frac{\sqrt 7 \times \sqrt 3}{2\sqrt 3\times \sqrt 3}\) = \(\frac{\sqrt{21}}{6}\))



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