Hello,
A:
2x²-7x-4=0
==>2x²-8x+x-4=0
==>2x(x-4)+1(x-4)=0
==>(x-4)(2x+1)=0
==>(x=4) or (x=-1/2)
B: where is the sign "=" !!!!!!!!!!!!!!!!!!
81x^-1=(9x²+1)(3x+1)(3x-1) I can not go any further.
C)
2x²-32=0
==>x²-16=0
==>(x+4)(x-4)0
==>x=-4 or x=4
D:
where is the sign "="!!!!!!!!!!!!!!!!!!!!!!!!
x^2-7x+12=(x-4)(x-3) but I can not go ant further....