UPSC NDA Math Model Paper 7

First evaluate the determinant of the given matrix:
det(A) = 4(15 - 0) – 7(-5 + 4) + 1(0 + 6)
= 4(15) -7(-1) + 1(6)
= 60 + 7 + 6
= 73
Now using the property the value of det(3A) is:
det(3A)=33‌det(A)
= 27 × 73
=1971