(2x²-5x+2)(3x²+5x+2)
=(2x²-5x+2)(2x²+5x+2+x²)
=(2x²-5x+2)(2x²+5x+2)+(2x²-5x+2)*x²
=(2x²+2)²-(5x)²+2x^4-5x^3+2x²
=4x^4+8x²+4-25x²+2x^4-5x^3+2x²
=6x^4-5x^3-15x²+4
(2x²-5x+2)(3x²+5x+2)
=(2x²-5x+2)(2x²+5x+2+x²)
=(2x²-5x+2)(2x²+5x+2)+(2x²-5x+2)*x²
=(2x²+2)²-(5x)²+2x^4-5x^3+2x²
=4x^4+8x²+4-25x²+2x^4-5x^3+2x²
=6x^4-5x^3-15x²+4