Question

1.
If $x <> (sqrt xy)/(|x-y|), find
4 <> (9 <> 1) to the nearest tenth.
<>=diamond
This is a function, where the "diamond" represents a function.

2.
If f(x) = 3x^2 - 5, what is the value of f(f(-1))?

Answer 1

If I read this right,

x<>y = √(xy)/|x-y|
so,
9<>1 = √(9*1)/|9-1| = 3/8
4<>(3/8) = √(4*3/8)/|4-3/8| = √(3/2)/(31/8) = 4/31 √6

f(-1) = 3*1-5 = -2
f(-2) = 3*4-5 = 7
so, f(f(-1)) = 7

Answer 2

4-3/8 = 29/8, not 31/8