Question

The answers to 13 and 20 and how there done.

Answer 1

The sum and product of two functions
`f(x)` and
`g(x)`, i.e.
`(f+g)(x)` and
`(f\cdot g)(x)` respectively, are simply defined as the sum and product of the expressions that define each function.

So, as for exercise 13, we have

`(f\cdot g)(x) = f(x)\cdot g(x) = (2x^3-5x^2)(2x-1) = 4 x^4- 12 x^3 +5 x^2`

Similarly, as for exercise 20, we have

`(g + f)(t) = g(t) + f(f) = (2t+5) + (-t^2+5) = -t^2 + 2t + 10`