125

a)
\frac{7x-3}{2x+3}=0
7x-3=0{,}\ x\ne-\frac{3}{2}
x=\frac{7}{3}
b)
\frac{x^2-1}{1-x}=0
x^2-1=0{,}\ x\ne1
x^2=1
x=1\ tai\ -1
x=-1{,}\ koska\ x\ne1