Question

Tính 

a/ ( y^2 - 4 )^2 - ( y - 2 ) . ( 2 + y ) . ( y^2 + 4 )

b/ ( a^2 + a - 4 ) . ( a^2 - a + 4 )

c/ ( 9n^4 - 4n^2 + 4n - 1 ) : ( 3n^2 + 1 - 2n )

Answer 1

a) \(...=\left(y^2-4\right)^2-\left(y^2-4\right)\left(y^2+4\right)\)

\(=y^4-8y^2+16-\left(y^4-16\right)\)

\(=y^4-8y^2+16-y^4+16\)

\(=16-8y^2=8\left(2-y^2\right)\)

b) \(...=\left(a^2\right)^2-\left(a-4\right)^2\)

\(=a^4-\left(a^2-8a+16\right)\)

\(=a^4-a^2+8a-16\)

c) \(...=\left[\left(3n^2\right)^2-\left(4n^2-4n+1\right)\right]:\left(3n^2+1-2n\right)\)

\(=\left[\left(3n^2\right)^2-\left(2n-1\right)^2\right]:\left(3n^2-2n+1\right)\)

\(=\left(3n^2+2n-1\right)\left(3n^2-2n+1\right):\left(3n^2-2n+1\right)\)

\(=3n^2+2n-1\)