Factorise :
$84-2 r-2 r^{2}$
Factorise :
$84-2 r-2 r^{2}$
In order to factorise $84-2 r-2 r^{2}$, we have to find two numbers $p$ and $1$ such that $p+q=-2$ and $pq =-168.$
$\therefore \quad 84-2 r-2 r^{2}=-2 r^{2}-2 r+84$
$=-2 r^{2}-14 r+12 r+84$
$=-2 r(r+7)+12(r+7)$
$=(r+7)(-2 r+12)$
$=-2(r+7)(r-6)=-2(r-6)(r+7)$
Similar Questions
Expand the following:
$(3 a-5 b-c)^{2}$
Expand the following:
$(3 a-5 b-c)^{2}$
Factorise
$25 x^{2}+9 y^{2}+64+30 x y-48 y-80 x$
Factorise
$25 x^{2}+9 y^{2}+64+30 x y-48 y-80 x$
From the following polynomials find out which of them has $(x-1)$ as a factor
$x^{3}+6 x^{2}-9 x-14$
From the following polynomials find out which of them has $(x-1)$ as a factor
$x^{3}+6 x^{2}-9 x-14$
Find the value of the polynomial $3 x^{3}-4 x^{2}+7 x-5,$ when $x=-3$
Find the value of the polynomial $3 x^{3}-4 x^{2}+7 x-5,$ when $x=-3$
$85 \times 75=\ldots \ldots \ldots$
$85 \times 75=\ldots \ldots \ldots$