Quadratic functions and graphs

There are 17 NRICH Mathematical resources connected to Quadratic functions and graphs
Fence it
problem
Favourite

Fence it

Age
11 to 14
Challenge level
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If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?
What's that graph?
problem
Favourite

What's that graph?

Age
14 to 18
Challenge level
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Can you work out which processes are represented by the graphs?

Parabolic Patterns
problem
Favourite

Parabolic patterns

Age
14 to 18
Challenge level
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The illustration shows the graphs of fifteen functions. Two of them have equations $y=x^2$ and $y=-(x-4)^2$. Find the equations of all the other graphs.

Parabella
problem
Favourite

Parabella

Age
16 to 18
Challenge level
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This is a beautiful result involving a parabola and parallels.

Parabolas Again
problem
Favourite

Parabolas again

Age
14 to 18
Challenge level
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Here is a pattern composed of the graphs of 14 parabolas. Can you find their equations?
Minus One Two Three
problem
Favourite

Minus one two three

Age
14 to 16
Challenge level
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Substitute -1, -2 or -3, into an algebraic expression and you'll get three results. Is it possible to tell in advance which of those three will be the largest ?
Janusz asked
problem

Janusz asked

Age
16 to 18
Challenge level
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In y = ax +b when are a, -b/a, b in arithmetic progression. The polynomial y = ax^2 + bx + c has roots r1 and r2. Can a, r1, b, r2 and c be in arithmetic progression?
Grid Points on Hyperbolas
problem

Grid points on hyperbolas

Age
16 to 18
Challenge level
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Find a condition which determines whether the hyperbola y^2 - x^2 = k contains any points with integer coordinates.
Converse
problem

Converse

Age
14 to 16
Challenge level
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Clearly if a, b and c are the lengths of the sides of an equilateral triangle then a^2 + b^2 + c^2 = ab + bc + ca. Is the converse true?
Consecutive Squares
problem

Consecutive squares

Age
14 to 16
Challenge level
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The squares of any 8 consecutive numbers can be arranged into two sets of four numbers with the same sum. True of false?