[tex](x+6)(x+9)=x^2+9x+6x+54=x^2+15x+54 \\\\(x-5)(x+2)=x^2+2x-5x-10=x^2-3x-10\\\\(x-1)(x-7)=x^2-7x-x+7=x^2-6x+7\\\\(4x+9)(3x+8)=12x^2+32x+27x+72=12x^2+59x+72\\\\(3x-8)(2x-1)=6x^2-3x-16x+8=6x^2-19x+8\\\\(x+9) ^2=x^2+2\cdot x\cdot9+9^2=x^2+18x+81 \\\\(3x+2)^2=(3x)^2+2\cdot3x\cdot2+2^2=9x^2+12x+4[/tex]
