Question

factorise-7x^3-3x^2-21x+9

Answer 1

The question:
$7 x^{3} -3 x^{2} -21x+9$
⇒$x^{2} (7x-3)-3(7x-3)$
⇒$( x^{2} -3)(7x-3)$
⇒$( x^{2} -( \sqrt{3})^{2} )(7x-3)$
⇒$(x+ \sqrt{3} )(x- \sqrt{3} )(7x-3)$
Ans:$(x+ \sqrt{3} )(x- \sqrt{3} )(7x-3)$
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