Question

Two secants of a circle meet in a point out side to the circle. One Secant has 4 and x. The other Secant is 5 and 4. What will be x?

Answer 1

"One Secant has 4 and x" is not clear.
Is 4 the length of the entire secant or just the part inside the circle?

In general, if you have two secants to the same circle

(whole of secant #1)(outside part of secant#1) = (whole of secant#2)(outside part of secant#2)

So look at your diagram, and plug the values into my equation.

Answer 2

thanks