Помогите 905 задание

Question

Помогите 905 задание

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Answer 1

1)(a²-1)(a²+1)=a^4-1
2)(1-4b²)(1+4b²)=1-8b^4
3)9-4a²b^4+4a²b^4=9
4)(\frac{ a^{2} }{4} -25+25= \frac{ a^{2} }{2} 

Comments

4)a²/4-25+25=a²/4