Let P be the plane passing through the line 1x−1=−3y−2=7z+5 and the point (2,4,−3). If the image of the point (−1,3,4) in the plane P is (α,β,γ), then α+β+γ is equal to
(A)12
(B)11
(C)9
(D)10✓ Correct
Answer: (D)
Solution
The line passes through A(1,2,−5) with direction vector d=(1,−3,7). The plane also passes through P(2,4,−3), so AP=(1,2,2).