Answer:
8
Step-by-step explanation:
All the factors of 8 and 16 are 1;2;4;8
X^2-4x+4 is the answer, to save you points next time, use an app called M8thw8y
using hyp²=opp²+adj²
x²=21²+20²
x²=441+400
x²=841
x =/841
x=29
