નીચેની પ્રત્યેક અભિવ્યક્તિમાં $x^2$ નો સહગુણક જણાવો : 

$(i)$ $(x-1)(3 x-4)$

$(ii)$ $(2 x-5)\left(2 x^{2}-3 x+1\right)$

$(i)$ The given polynomial can be written as:

$(x-1)(3 x-4)=3 x^{2}-4 x-3 x+4$

$=3 x^{2}-7 x+4$

So, coefficient of $x^{2}$ in the given polynomial is $3 .$

$(ii)$ The given polynomial can be written as:

$(2 x-5)\left(2 x^{2}-3 x+1\right)=4 x^{3}-6 x^{2}+2 x-10 x^{2}+15 x-5$

$=4 x^{3}-16 x^{2}+17 x-5$

So, the coefficient of $x^{2}$ in the given polynomial is $-16 .$