若x²+mx-15=(x+3)(x+n),则m的值为( ) A.-5 B.5 C.-2 D.2
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![若x²+mx-15=(x+3)(x+n),则m的值为( ) A.-5 B.5 C.-2 D.2](/uploads/image/z/3177500-68-0.jpg?t=%E8%8B%A5x%26%23178%3B%2Bmx-15%3D%EF%BC%88x%2B3%EF%BC%89%EF%BC%88x%2Bn%EF%BC%89%2C%E5%88%99m%E7%9A%84%E5%80%BC%E4%B8%BA%EF%BC%88+%EF%BC%89+A.-5+B.5+C.-2+D.2)
若x²+mx-15=(x+3)(x+n),则m的值为( ) A.-5 B.5 C.-2 D.2
若x²+mx-15=(x+3)(x+n),则m的值为( ) A.-5 B.5 C.-2 D.2
若x²+mx-15=(x+3)(x+n),则m的值为( ) A.-5 B.5 C.-2 D.2
x²+mx-15=(x+3)(x+n)
x²+mx-15=x²+(n+3)x+3n
所以m=n+3
-15=3n
所以n=-5
m=n+3=-2
选C