3. (3x+5)²=9x²+2*3x*5+5²= 9x²+30x+25 y=ax²+bx+c, so a=9,b=30,c=25, a+b+c=9+30+25= 64
4.how I understand, it should be solved the equation 8^(2x-1)=4^(3x+4)
(2^3)^(2x-1) = (2^2)^(3x+4) 2^(3*(2x-1))=2^(2*(3x+4)) 3*(2x-1)= 2*(3x+4) 6x-3=6x+8 -3=8 false, so this equation has NO solutions (if the equation was written correctly)
