Question

2. Suppose that a, b all real numbers. Show that Ia bI = IaI * IbI
3. Suppose that a, b all real numbers. Show that ab (less than or equal to symbol) IaI IbI
4. Suppose that a,b all real numbers
a) use the previous excercise to show that Ia+bI (less than or equal to symbol) IaI + IbI. This inequality is call the triangle inequality.
b) use part a to show that
Ia+bI (less than or equal to symbol) IaI - IbI