Question

(X²-2)(x²+2)=?
(a²+1)(1-a²)=?
(2x²+3y)(3y-2x²)=?
(4/5x-1)(4/5x+1)=?
(a³-2x)(a³+2x)

Answer 1

$\displaystyle\bf\\(x^{2} -2)(x^{2} +2)=(x^{2} )^{2} -2^{2} =x^{4} -4\\\\\\(a^{2} +1)(1-a^{2} )=1^{2} -(a^{2} )^{2}=1-a^{4} \\\\\\(2x^{2} +3y)(3y-2x^{2} )=(3y)^{2} -(2x^{2} )^{2} =9y^{2} -4x^{4} \\\\\\\Big(\frac{4}{5} x-1\Big)\Big(\frac{4}{5} x+1\Big)=\Big(\frac{4}{5} x\Big)^{2} -1^{2} =\frac{16}{25} x^{2} -1\\\\\\(a^{3}-2x)(a^{3} +2x)= (a^{3} )^{2} -(2x)^{2} =a^{6} -4x^{2}$