Question Details

If p = 6, q = −3, then the value of p3 – 3p2 + 3p + 3q + 3q2 + q3 is:

Options

A

–61

B

61

C

117

D

–117

Show Answer

Correct Answer :

Option C

117

Solution :

The correct option is 117.

We are given the following values for the variables:
p=6
q=-3

We need to find the value of the algebraic expression:
E=p3-3p2+3p+3q+3q2+q3

Method 1: Direct Substitution

First, calculate each term involving p using p=6:
p3=63=216
-3p2=-3(62)=-3(36)=-108
3p=3(6)=18

Next, calculate each term involving q using q=-3:
3q=3(-3)=-9
3q2=3((-3)2)=3(9)=27
q3=(-3)3=-27

Now, add all the calculated values together:
E=216-108+18-9+27-27

Simplifying step-by-step:
E=(216-108)+18-9+(27-27)
E=108+18-9+0
E=126-9
E=117

Method 2: Using Algebraic Identities

We can rewrite the expression using algebraic identities for cubic terms:
Recall that (p-1)3=p3-3p2+3p-1 and (q+1)3=q3+3q2+3q+1.

Adding these two expansions:
(p-1)3+(q+1)3=(p3-3p2+3p-1)+(q3+3q2+3q+1)
(p-1)3+(q+1)3=p3-3p2+3p+3q+3q2+q3

Thus, the expression is equivalent to:
E=(p-1)3+(q+1)3

Substitute p=6 and q=-3 into this simplified form:
E=(6-1)3+(-3+1)3
E=53+(-2)3
E=125-8
E=117

Both methods yield the final result of 117.

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