2.4.1 Multiplication of a Matrix by a Number (Sample Questions) February 1, 2022January 25, 2021 by Example 1: Express the following as single matrix. (a) 3 ( 1 − 4 − 3 2 ) + 2 ( − 3 1 3 − 4 ) (b) 2 ( − 1 0 9 − 4 ) − 4 ( − 2 2 3 − 6 ) − 1 3 ( − 9 − 3 − 6 15 ) Solution: (a) 3( 1 −4 −3 2 )+2( −3 1 3 −4 ) =( 3×1 3×(−4) 3×(−3) 3×2 )+( 2×(−3) 2×1 2×3 2×(−4) ) =( 3 −12 −9 6 )+( −6 2 6 −8 ) =( 3+(−6) −12+2 −9+6 6+(−8) ) =( −3 −10 −3 −2 ) (b) 2( −1 0 9 −4 )−4( −2 2 3 −6 )− 1 3 ( −9 −3 −6 15 ) =( −2 0 18 −8 )−( −8 8 12 −24 )−( 1 3 ×(−9) 1 3 ×(−3) 1 3 ×(−6) 1 3 ×15 ) =( −2 0 18 −8 )−( −8 8 12 −24 )−( −3 −1 −2 5 ) =( −2−(−8)−(−3) 0−8−(−1) 18−12−(−2) −8−(−24)−5 ) =( 9 −7 8 11 )
Hello, for Question (a), the answer for the right bottom number should be 6 + (-8) = -2 , not 6 – (-8) = 14
Hello, the answer for b is (9,-7,8,11) because of 18 – 12 -(-2) is 8
Dear Nadin Husin,
thanks for pointing out our mistake, correction had been made accordingly.
Hello, for Question (a), the answer for the right bottom number should be 6 + (-8) = -2 , not 6 – (-8) = 14
Dear Wayne,
thanks for pointing out our mistake, correction had been made accordingly.