<h3>
Answer: x = -5, -4, 4 and 5.</h3><h3>All four zeros are real solutions.</h3>
Step-by-step explanation:
Given the polynomial equation
.
Adding 400 on both sides to get rid 400 from right side and set 0 on right side, we get
.
.
Factoring by product sum rule.
We need product of 400 and sum upto -41.
We can see that 400 = -25 × -16 = 400 and -25-16 = -41.
Therefore,

Making it into two groups, we get

Factoring out GCF of each group, we get


Factoring out
and
separately by difference of the squares identity
, we get
and
.
Therefore,

Applying zero product rule,
x-5=0
x+5=0
x-4=0 and
x+4=0.
Therefore,
<h3>x = -5, -4, 4 and 5.</h3><h3>All four zeros are real solutions.</h3>