Question

Show that 1 and -2 are zero's of polynomial 2x3 + x2 - 5x + 2

Answer 1

put 1and -2 in the equation one by one, if you get zero from this equation. it satisfies

Answer 2

For 1
2*3+1*2-5*1+2=6+2-5+2
10
For -2
2*3+-2*2-5*-2+2=6-4+10+2
2+12=14