(5x2+3)(3-5x2)

To simplify the expression \((5x^2 + 3)(3 - 5x^2)\), we can use the distributive property (also known as the FOIL method for binomials):

1. Multiply the first terms: \[ 5x^2 \cdot 3 = 15x^2 \]

2. Multiply the outer terms: \[ 5x^2 \cdot (-5x^2) = -25x^4 \]

3. Multiply the inner terms: \[ 3 \cdot 3 = 9 \]

4. Multiply the last terms: \[ 3 \cdot (-5x^2) = -15x^2 \]

Now, combine all these results together: \[ 15x^2 - 25x^4 + 9 - 15x^2 \]

Now combine like terms:

• The \(15x^2\) and \(-15x^2\) cancel each other out.

This leaves us with: \[ -25x^4 + 9 \]

Thus, the simplified expression is: \[ \boxed{-25x^4 + 9} \]