If a =9i-7j+5k and b=3i-2j-6k then the value of (a+b).(a-b)
Answers
Answered by
6
Explanation:
a+b=(9i-7j+5k) +(3i-2j-6k)
=12i-9j-k
a-b=(9i-7j+5k)-(3i-2j-6k)
=6i-5j+11k
(a+b).(a-b)=(12i-9j-k).(6i-5j+11k)
=72-45-11
=72-56
=16
Answered by
26
Answer:
106
Explanation:
a + b = ( 9i - 7j + 5k ) + ( 3i - 2j - 6k )
= 12i - 9j - k
a - b = ( 9i - 7j + 5k ) - ( 3i - 2j - 6k )
= 6i - 5j + 11k
(a+b) . (a-b) = ( 12i - 9j - k ) . ( 6i - 5j + 11k )
= 72 + 45 - 11
= 117 - 11
= 106
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