Expanding and factorising quadratics

There are 38 NRICH Mathematical resources connected to Expanding and factorising quadratics
2-Digit Square
problem
Favourite

2-digit square

Age
14 to 16
Challenge level
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A 2-Digit number is squared. When this 2-digit number is reversed and squared, the difference between the squares is also a square. What is the 2-digit number?
Pair Products
problem
Favourite

Pair products

Age
14 to 16
Challenge level
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Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?

Polar Flower
problem

Polar flower

Age
16 to 18
Challenge level
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This polar equation is a quadratic. Plot the graph given by each factor to draw the flower.
Never Prime
problem

Never prime

Age
14 to 16
Challenge level
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If a two digit number has its digits reversed and the smaller of the two numbers is subtracted from the larger, prove the difference can never be prime.
Leftovers
problem

Leftovers

Age
14 to 16
Challenge level
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Weekly Problem 26 - 2008
If $n$ is a positive integer, how many different values for the remainder are obtained when $n^2$ is divided by $n+4$?
Spot the difference
problem

Spot the difference

Age
16 to 18
Challenge level
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If you plot these graphs they may look the same, but are they?
Geometric Parabola
problem

Geometric parabola

Age
14 to 16
Challenge level
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Explore what happens when you draw graphs of quadratic equations with coefficients based on a geometric sequence.
Unit interval
problem

Unit interval

Age
16 to 18
Challenge level
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Can you prove our inequality holds for all values of x and y between 0 and 1?
Powerful Factors
problem

Powerful factors

Age
16 to 18
Challenge level
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Use the fact that: x²-y² = (x-y)(x+y) and x³+y³ = (x+y) (x²-xy+y²) to find the highest power of 2 and the highest power of 3 which divide 5^{36}-1.
Two Cubes
problem

Two cubes

Age
14 to 16
Challenge level
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Two cubes, each with integral side lengths, have a combined volume equal to the total of the lengths of their edges. How big are the cubes? [If you find a result by 'trial and error' you'll need to prove you have found all possible solutions.]