Question

How do you multiply `(2r - 5)(r + 10)`?

Answer 1

use f.o.i.l
2 `r^2`+15r-50

Explanation:

multiply the first two terms(first)
multiply the two outside terms(outside)
multiply the two inside terms(inside)
multiply the two last terms(last)
f.o.i.l
so it's (2rr) + (2r10)+(-5r)+(-510)
and then combine like terms and the answer should be:
2 `r^2`+15r-50