Question 325759
Your hyperbola is of the form y^2/b^2 - x^2/a^2 = 1.

We need to find a and b to start with.

b^2 = 4

sqrt{b^2} = sqrt{4}

b = 2

a^2 = 49

sqrt{a^2} = sqrt{49}

a = 7

We now know that a = 7 and b = 2.

The foci will be points (-c,0) and (c,0).  This means we need to find c.

We can c using c = sqrt{a^2 + b^2}.

c = sqrt{7^2 + 2^2}

c = sqrt{49 + 4}

c = sqrt{53}

The foci are (-sqrt{53}, 0) and (sqrt{53}, 0).

Did you follow?