You may also like
Real(ly) Numbers
If x, y and z are real numbers such that: x + y + z = 5 and xy + yz + zx = 3. What is the largest value that any of the numbers can have?
Pair Squares
The sum of any two of the numbers 2, 34 and 47 is a perfect square. Choose three square numbers and find sets of three integers with this property. Generalise to four integers.
Escriptions
For any right-angled triangle find the radii of the three escribed circles touching the sides of the triangle externally.
Age 16 to 18
Challenge Level
Solve the following system of equations to find the values of $x$, $y$ and $z$. $${\frac {xy}{x+y}}=\frac 1 2$$ $${\frac {yz} {y+z}} =\frac 1 3$$ $${\frac{xz}{x+z}} = \frac 1 7$$
Can you show how the first equation can be arranged to get $\dfrac 1 x + \dfrac 1 y =2$?
Copyright © 1997 - 2023. University of Cambridge.
All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.