1. m/n=5, m= 5n,
(5n)²-25n²=25n²-25n²=0
2.3/x=5/y
3y=5x
y/x=5/3
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)
