I assume the first term of the trinomial is 2x^2, and you left out the exponent.
Multiply each term of the binomial by each term of the trinomial.
Then collect like terms.
[tex] (x - 5)(2x^2 + 3x - 1) = [/tex]
[tex] = x * 2x^2 + x * 3x + x * (-1) - 5 * 2x^2 - 5 * 3x - 5 * (-1) [/tex]
[tex] = 2x^3 + 3x^2 - x - 10x^2 - 15x + 5 [/tex]
[tex] = 2x^3 - 7x^2 - 16x + 5 [/tex]
