3x(x-2)-5x(x+3)

To simplify the expression 3x(x-2)-5x(x+3), we can use the distributive property.

First, let's expand the expression:

3x(x-2) = 3x * x - 3x * 2 = 3x^2 - 6x

-5x(x+3) = -5x * x - 5x * 3 = -5x^2 - 15x

Now, we can combine the like terms:

(3x^2 - 6x) - (5x^2 + 15x) = 3x^2 - 6x - 5x^2 - 15x

To combine the like terms, we add or subtract the coefficients of the same degree variables:

(3x^2 - 5x^2) + (-6x - 15x) = -2x^2 - 21x

Therefore, the simplified expression is -2x^2 - 21x.