3x²-6√2xy-3y²=3（x²-2√2xy-y²）=3(x²-2√2xy＋2y²-3y²)=3(x-√2y)²-9y²=3【(x-√2y)²-3y²】=3【(x-√2y-√3y)(x-√2y+√3y)】2.-3a²+4ab+2b²=...