very frustrating ellipse..?

Question

i have a question on my homework that asks me to write an equation to an ellipse when i know the major axis, which is 6 and the foci being at (0, +/-1)

everytime i solve it and i try to find out what b^2 is i keep getting some really wierd decimal and negative number.
so far i have

x^2/? + y^2/9=1

i just cant figure out how i can find b^2
please help!

Answer 1

b² = a² - c² = 9 - 1 = 8