a) is completing the square method
so it is (3x+2)2+3
b) 0<f(x)<=1/3
this is becuz no value of f(x) can be less than zero....since a negative x will be squared to give a positive value...
the greatest value of f(x) would be when denominator is least...this will be possible only when denominator is 3 and bracket is 0. hence 1/3