Question

Помогите плиз, даю 40!

Answer 1

$\displaystyle\bf\\X=-20+15t-2,5t^{2} \\\\\\V_{x} =\Big(-20+15t-2,5t^{2} \Big)'=\Big(-20\Big)'+15\cdot t'-2,5\cdot\Big(t^{2} \Big)'=\\\\\\=0+15\cdot 1-2,5\cdot 2t=15-5t\\\\\\Otvet: \ V_{x} =15-5t$