Đại số 8!

H

harrypham

$$\begin{aligned} 4(2xy+4)^2-(x^2+4y^2-17)^2 & = (4xy+8)^2-(x^2+4y^2-17)^2 \\ & = (4xy+8-x^2-4y^2+17)(4xy+8+x^2+4y^2-17) \\ & = \left[ 5^2 -(x^2-4xy+(2y)^2) \right] \left[ ((2y)^2+4xy+x^2)-9 \right] \\ & = \left[ 5^2-(x-2y)^2 \right] \left[ (2y+x)^2-3^2 \right] \\ & = (5-x+2y)(5+x-2y)(2y+x-3)(2y+x+3) \end{aligned}$$
 
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