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4.9 SPM Practice (Short Questions)

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4.9.2 Matrices, SPM Practice (Short Questions)
Question 5:
Given that (3 x)(x−1)=(18),  find the value of x.

Solution:
(3 x)(x−1)=(18)
[3 × x + x (–1)] = (18)
3x – x = 18
2x = 18
x = 9



Question 6:
(34−23)(5−2)=

Solution:
(34−23)(5−2)=((3)(5)+(4)(−2)(−2)(5)+(3)(−2))=(15−8−10−6)=(7−16)



Question 7:
(24−3401)(1−3)=

Solution:
Order of the product of the two matrices
=(3×2)(2×1)=(3×1)

(24−3401)(1−3)=(2(1)+4(−3)(−3)(1)+0(−3)(4)(1)+1(−3))=(2−12−3+04−3)=(−10−31)



Question 8:
(1 −1  2)(51−3204)=

Solution:
Order of the product of the two matrices
=(1×3)(3×2)=(1×2)

(1 −1  2)(51−3204)=
= (1×5 + (–1)(–3) + (2)(2)  1×1 + (–1)(0) + (2)(4))
= (5 + 3 + 4   1 + 0 + 8)
= (12   9)