31.21.
1) (a-y)(a+y)(a^ 2 +y^ 2 )

2) (7x + 1)(7x - 1) * (49x ^ 2 + 1)

3) (x - 6y ^ 3) ^ 2 * (x + 6y ^ 3) ^ 2

4) (8+x^ 3 )(8-x^ 3 )*(64+x^ 6 )

5) (25x^ 2 +y^ 2 )(5x+y)(5x-y)

6)(81a^ 4 +16b^ 4 )(9b^ 2 +4a^ 2 )(4a^ 2 -9b^ 2 )

помогите пожалуйста!​

Қысқаша көбейту формулаларын қолданайық.

1) \[(a-y)(a+y)(a^2+y^2)=(a^2-y^2)(a^2+y^2)=a^4-y^4\]

2) \[(7x+1)(7x-1)(49x^2+1)=(49x^2-1)(49x^2+1)=2401x^4-1\]

3) \[(x-6y^3)^2(x+6y^3)^2=(x^2-36y^6)^2=x^4-72x^2y^6+1296y^{12}\]

4) \[(8+x^3)(8-x^3)(64+x^6)=(64-x^6)(64+x^6)=4096-x^{12}\]

5) \[(25x^2+y^2)(5x+y)(5x-y)=(25x^2+y^2)(25x^2-y^2)=625x^4-y^4\]

6) \[(81a^4+16b^4)(9b^2+4a^2)(4a^2-9b^2)\]

Сначала:

\[(9b^2+4a^2)(4a^2-9b^2)=16a^4-81b^4\]

Тогда:

\[(81a^4+16b^4)(16a^4-81b^4)=1296a^8-6305a^4b^4-1296b^8\]

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