1.因式分解:x²-3x²-28
2.若x-y=2,x²-y²=10,则x+y=_____.
1.因式分解:x²-3x²-28
2.若x-y=2,x²-y²=10,则x+y=_____.
1、(X+4)*(X-7)
2、X+Y=5 (X-Y)*(X+Y)=X2-Y2=10,所以X+Y=5
1...X2-3X2-28=(X+4)(X-7)
2...6
题目是不是错了?应该是X^3-3X^2-28吧?
=x^3-1+3(x^2-9)
=(x-1)(x^2+x+1)+3(x-3)*(X+3)
1.你确定是这样的??
2. 5