Other equations

There are 22 NRICH Mathematical resources connected to Other equations
Building Tetrahedra
problem

Building Tetrahedra

Age
14 to 16
Challenge level
filled star filled star empty star
Can you make a tetrahedron whose faces all have the same perimeter?
Real(ly) numbers
problem

Real(ly) numbers

Age
16 to 18
Challenge level
filled star filled star empty star
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?