Question

28. If (x + 2) and (x - 1) are factors of the polynomial p(x) = x° +10x² + mx +n
then
(a) m = 5, n = -3
(b) m = 7, n=-18
(c) m = 17, n=-8
(d) m = 23, n=-19
​

Answer 1

Answer:

option C

Step-by-step explanation:

Here, x+2 is a factor of x

3

+10x

2

+mx+n

x=−2

(−2)

3

+10(−2)

2

+m(−2)+n=0

−8+40=2m−n

2m−n=32 .....(i)

Again, x−1 is a factor of x

3

+10x

2

+mx+n

x=1

1+10+m+n=0

m+n=−11 .....(ii)

Adding (i) and (ii). we get,

3m=21

m=7

By putting m in (i). we get,

2(7)−n=32

−n=18

n=−18

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