Answer:
B is the correct answer.
Step-by-step explanation:
4x = 20
x = 5
a^4+b^4=(a^2)^2+(b^2)^2
=(a^2+b^2)^2–2a^2b^2
=(a^2+b^2)^2—(√ 2ab)^2
=(a^2+√ 2ab+b^2)(a^2-√ 2ab+b^2)
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