Question

Determine the solution set of x2 - 80 = 0

Answer 1

x^2 -80=0
x^2 =80
x =sqrrt 80

Answer 2

x² - 80 = 0
Add 80
to each side: x² = 80

Square root
each side: x = √80

Look it up: x = + 8.944... (rounded)
and
x = - 8.944... (rounded).
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Here's a cleaner solution:

x² - 80 = 0
Add 80
to each side: x² = 80

Square root
each side: x = √80

But 80 = 16 · 5

So √80 = √16 · √5

√16 = 4, so x = 4 √5