Answer:
value of a is -19
value of b is 10
Step-by-step explanation:
Given
p(x) = 6x³ + ax² + 9x + b
Since it is given (x-2) & (2x-1) are the factors of given polynomial p(x) .
So, x = 2 & x = -1/2 are the solutions of given polynomial .
when x = 2
p(2) = 6(2)³ + a(2)² + 9 (2) + b = 0
p(2) = 6×8 + 4a + 18 + b = 0
p(2) = 48 + 4a + 18 + b = 0
p(2) = 66 + 4a + b = 0
4a + b = -66 -------(i)
Now ,
when x = -½
p(-½) = 6(-½)³ + a (-½)² + 9(-½) + b = 0
6 × (-⅛) + a/4 - 9/2 + b = 0
-3/4 + a/4 - 9/2 + b = 0
-3 + a -18+4b/4 = 0
-21 + a + 4b = 0
a + 4b = 21 -------(ii)
Now, multiplying the equation (ii) by 4 we get
4a + 16b = 84 -----(iii)
Substracting equation (i) from (iii) we obtain
15b = 150
b = 150/15
b = 10
Now, putting the value of b = 10 in equation (ii) we get
a + 40 = 21
a = 21-40
a = -19
So, the required value of a & b are 10 & -19 respectively .
