Question

if (x-2) and (x+3) is a factor of x³ +ax²+bx-30 find a and b​

Answer 1

Answer:

a=20,b=-29

Step-by-step explanation:

When x=2

Then x3 + ax2 + bx-30

8+4a+2b-30 (1)

When x=-3

Then. X3+ax2+bx-30

27+9a-3b-30. (2)

Multiply equation 1st to 3

24+12a+6b-90. (3)

Multiply equation 2nd to 2

54+18a-6b-60. (4)

Subtract equation 3 from 4

30+6a -0-150

=6a-120

6a=120

a=20

Then substitute the value of a in equation 1st

8+4a+2b-30

, =8+4×20+2b-30

=8+80+2b-30

=88+2b-30

=58+2b

2b=-58

b=-29