Remember that

so

(a+ b)^2 = a^2 + 2ab + b^2
1. x^2 + 2x*9i + (9i)^2 = x^2 + 18xi - 81
2. x^2 + 2x*(3+5i)+ (3+5i)^2 = x^2 + 6x + 10xi+ 9+30i-25 = x^2 - 16 + 30i + 6x + 10xi
Answer:
x=9 or -9
Step-by-step explanation:
the equation is:x^2-8=420-347
420-347=73
if x=9 then 81-8=73
and then 73=73
so x=9
hope this helps!
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