without actual division,prove that (x-2) is a factor of the polynomial 3x^3-13x^2+8x+12.Also factorise it completely
Answers
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Answer:
If (x-2) is a factor of p(x)
p(x) = 0
p(2) = 3x^3 - 13x^2 + 8x + 12
3(2)^3 - 13(2)^2 + 8(2) + 12
3 x 8 - 13 x 4 + 16 + 12
24 - 52 + 16 + 12
52 - 52 = 0
Hence, (x-2) is a factor of p(x)
x-2 ) 3x^3 - 13x^2 + 8x + 12( 3x^2 -7x^2 - 6
3x^3 - 6x^2
(-) (+)
-----------------------------------------
- 7x^2 + 8x + 12
- 7x^2 + 14x
(+) (-)
-----------------------------------------
-6x + 12
-6x + 12
(+) (-)
-----------------------------------------
0
---------------------------
Step-by-step explanation:
Now, (x-2) (3x^2 - 7x - 6)
(x-2) {3x^2 - ( 9 - 2 ) x - 6}
(x-2) { 3x^2 -9x + 2x - 6}
(x-2) {3x (x- 3) + 2 ( x - 3 )}
(x-2) (3x+2) (x - 3)