请高手分解因式,用十字交叉法
1.x²+2x-15 2.x²+8x+15 3.x²+14x+49 4.x²+8x+12 5.x²+7x-18 6.2x²+13x+15 7.2x²-7x+6 8.4x²-3x-52 9.5x²-9x-18 10.3x²+8x-3