Question

Factorise the following :

$21x {}^{2} - 8x - 4 = 0$
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Answer 1

Answer :- x = 2/3 and x = -2/7

Explanation :-

21x ^2 - 8x - 4 = 0

By Middle term splitting we get,

Multiplying the coefficient of the first term and the last term

21 × (- 4 ) = - 84

Factor of - 84 whose sum is the -8 is -14 and 6

= - 14 + 6

= 14 - 6

= 8

$\bold{21 {x}^{2} - 14x + 6x - 4 = 0}$

$\bold{7x(3x - 2)+2(3x - 2) = 0}$

$\bold{(3x - 2)(7x + 2) = 0}$

$\bold{x = \frac{2}{3} \: and \: x = \frac{ - 2}{7} }$

Therefore, we get x = 2/3 and x = -2/7

Answer 2

Hey dear ‼️

solution is in the attachment...

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