Answer:
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Step-by-step explanation:

To find f(−1) , substitute the values of x that's - 1 into f(x). That is for every x in f(x) replace it with - 1
That's

We have the final answer as

Hope this helps you
Answer:
x^3-4x^2+25x-100
Step-by-step explanation:
We have 2 roots -5i and 4. Using the conjugate root theorem for the root -5i, we know that 5i should be another root
Combining the roots into a polynomial gives us:
(x+5i)(x-5i)(x-4)
Expand:
(x^2 + 25)(x-4)
x^3-4x^2+25x-100
Simplifying √196 before doing the multiplication:
( √196 ÷ 7 ) × √48
= ( (√4 × √49) ÷ 7 ) × √48
= ( (2 × 7) ÷ 7 ) × √48
= 2√48
Simplifying √48:
= 2 × √16 × √3
= 2 × 4 × √3
= 8√3
which is irrational because it's a square root