Introduction:
In mathematics, a quadratic polynomial is a polynomial of degree two. It is expressed in the form of ax^2 + bx + c. In this question, we are given a quadratic polynomial t^2 - 15 and we need to find its zeros.

Steps to find the zeros:
To find the zeros of a quadratic polynomial, we need to follow the following steps:

1. Write the quadratic polynomial in the form of ax^2 + bx + c.
2. Substitute the values of a, b, and c in the quadratic formula.
3. Simplify the formula to get the value of x.
4. The value of x will be the zeros of the given quadratic polynomial.

Solution:
1. The given quadratic polynomial is t^2 - 15.
2. Comparing it with the standard form ax^2 + bx + c, we get:
a = 1, b = 0, c = -15.
3. Substituting the values in the quadratic formula, we get:
x = (-b ± √(b^2 - 4ac)) / 2a
= (-0 ± √(0^2 - 4(1)(-15))) / 2(1)
= ± √60 / 2
= ± √(4 x 15) / 2
= ± 2√15 / 2
= ± √15
4. Therefore, the zeros of the given quadratic polynomial t^2 - 15 are ± √15.

Conclusion:
In this way, we can find the zeros of a quadratic polynomial by using the quadratic formula. The zeros of a quadratic polynomial are the points where the polynomial intersects the x-axis.