If j = 9 and k = 9, what is the value of 3j 3k + jk ?

Question

If j = 9 and k = −9, what is the value of 3j − 3k + jk ?

(A) 135
(B) 54
(C) 27
(D) −27
(E) −54

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Dexter43 · Answer

Given that j = 9 , k= -9

now 
we need to calculate the value of 3j-3k+jk 
=> 3(j-k)+jk 
=> 3(9-(-9))+9(-9) 
=> 54-81
=> -27

option D  should be the correct answer

ManifestDreamMBA · Answer

3j − 3k + jk
3(j-k) + jk
3(9-(-9)) + 9*(-9)
9*3(2-3)
-27

Whoisdmx15 · Answer

Always try to reduce calculation time in such easier questions to make cushion for other problems:

j = 9 and k = −9, 
3j − 3k + jk ?
 We can immediately see that sign of k will be filpped in the second term (-3k)

Hence this essentially becomes 2*3*9 + 9*-9
This further becomes: 27*2 - 27*3
= 27*(2-3)
= -27

IMO Ans D

eega · Answer

Given j=9,k=-9
3j-3k+jk = 27+27-81 = -27  (Option D)

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