Factorise:84 - 2r - 2r^2 | vedclass

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(B) To factorise $84 - 2r - 2r^2$,first rearrange the terms in descending order of powers of $r$:$-2r^2 - 2r + 84$Factor out the common term $-2$:$-2(

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$-2(r - 6)(r + 7)$

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(B) To factorise $84 - 2r - 2r^2$,first rearrange the terms in descending order of powers of $r$:$-2r^2 - 2r + 84$Factor out the common term $-2$:$-2(r^2 + r - 42)$Now,factor the quadratic expression $r^2 + r - 42$. We need two numbers whose product is $-42$ and whose sum is $1$:These numbers are $7$ and $-6$.So,$r^2 + 7r - 6r - 42 = r(r + 7) - 6(r + 7) = (r - 6)(r + 7)$.Combining these,the final factorised form is:$-2(r - 6)(r + 7)$

Factorise:
$84 - 2r - 2r^2$

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Factorise:$84 - 2r - 2r^2$