Find the remainder when x3+3x2+3x+1 is divided by
(i) x+1 (ii) x-
(iii) x (iv) x+π
(v) 5+2x
Let, f(x) = x3+3x2+3x+1
(i) x + 1
Apply remainder theorem
⇒ x + 1 =0
⇒ x = - 1
Replace x by – 1 we get
⇒ x3+3x2 + 3x + 1
⇒ (-1)3 + 3(-1)2 + 3(-1) + 1
⇒ -1 + 3 - 3 + 1
⇒ 0
Hence, required remainder is 0.
(ii) x-
Apply remainder theorem
⇒ x – 1/2 =0
⇒ x = 1/2
Replace x by 1/2 we get
⇒ x3+3x2 + 3x + 1
⇒ (1/2)3 + 3(1/2)2 + 3(1/2) + 1
⇒ 1/8 + 3/4 + 3/2 + 1
Add the fraction taking LCM of denominator we get
⇒ (1 + 6 + 12 + 8)/8
⇒ 27/8
Hence, required remainder is 27/8
(iii) x = x – 0
By remainder theorem required remainder is equal to f (0)
Now, f (x) = x3+3x2+3x+1
f (0) = (0)3 + 3 (0)2 + 3 (0) + 1
= 0 + 0 + 0 + 1
= 1
Hence, required remainder is 1.
(iv) x+π = x – (-π)
By remainder theorem required remainder is equal to f (-π)
Now, f (x) = x3 + 3x2 + 3x + 1
f (- π) = (- π)3 + 3 (- π)2 + 3 (- π) + 1
= - π3 + 3π2 - 3π + 1
Hence, required remainder is - π3 + 3π2 - 3π + 1.
(v) 5 + 2x = 2 [x – ()]
By remainder theorem required remainder is equal to f ()
Now, f (x) = x3 + 3x2 + 3x + 1
f () =
)3 + 3 (
)2 + 3 (
) + 1
= + 3 *
+ 3 *
+ 1
= +
-
+ 1
=
Hence, required remainder is .