几道数学题,分解因式.1. 3X²+5XY-2Y²+X+9Y-4 2. X²-2根号2X-3 3. 3X²+4XY-Y²
问题描述：
几道数学题,分解因式.1. 3X²+5XY-2Y²+X+9Y-4 2. X²-2根号2X-3 3. 3X²+4XY-Y²
答
1. 3X²+5XY-2Y²+X+9Y-4 =(3x-y)(x+2y)+(x+9y)-4=(3x-y+4)(x+2y-1) 2. X²-2根号2X-3 =x^2-2√2x+2-5=(x-√2)^2-(√5)^2=(x-√2+√5)(x-√2-√5) 3. 3X²+4XY-Y²=[x+(-2+√7)y/3][x-(-2+√7)y...