Let Ax epsilon R0SolutionConsisder the map from A to B fx4x1

Solution

Consisder the map from A to B

f(x)=4x+1

Let, f(x)=f(y)

4x=4y

So, x=y

Let y in B

So, 4x+1=y gives

x=(y-1)/4

1<y<5

So, 0<y-1<4

So,   0<(y-1)/4<1

Hence, x =(y-1)/4 is in A

Hence, f is onto

So, f is a bijection from A to B

Hence, A and B have same cardinality