Topic Details (Notes format)

How to Multiply Matrices (2x2 and Beyond)

Subject: Mathematics

Book: Maths Mastery

Matrix multiplication is defined by taking the dot product of rows of the first matrix with columns of the second. For a 2×2 example, if A=[[a,b],[c,d]] and B=[[e,f],[g,h]], then A×B=[[ae+bg, af+bh],[ce+dg, cf+dh]]. The process generalizes to larger dimensions where inner dimensions must match. Matrix multiplication underlies transformations in 2D/3D graphics, network flows, Markov chains, or advanced linear systems. Gaining fluency is a key step in linear algebra, enabling big leaps in data analysis and computational problem-solving.

Practice Questions

If x:y = 4:5 and y:z = 2:3, what is x:z?

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A number is increased by 20% and then decreased by 10%. What is the net change?

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The base of a triangle is 10 cm and its height is 6 cm. What is its area?

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If x - y = 5 and x + y = 15, what is the value of x?

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A sum of money triples itself in 12 years at simple interest. What is the rate of interest per annum?

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If the radius of a circle is 7 cm, what is its circumference?

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A car covers a distance of 150 km in 2.5 hours. What is its average speed?

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The perimeter of a rectangle is 50 cm, and its length is 15 cm. What is its width?

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A number is increased by 20% and then decreased by 20%. What is the net change?

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A cube has a side length of 4 cm. What is its volume?

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