Answer:
(x-9)² = 60
Step-by-step explanation:
Hello,
A theorem with binomial squares states. I suggest you put more effort into this as it's extremely fundamental and essential in your growth in understanding mathematics.
(x-c)² = x² - 2xc + c²
Knowing so:
(x-9)² = x² - 18x + 81
But that's not it!!
In order to get the same value presented in the problem, we must bring all values to same side
In the problem:
x²-18x+21=0 (Add 8 to both sides)
Now in the answer choice, you must have:
x² - 18x + 81 = 60
since subtracting 60 from both sides yields the same result.
Have an amazing day.
