x^2+ax-9=(x+m)(x+n) m,n为正整数,则有自然数a的值?A.0,-8.8 B.正负8 C.0,-8 D.0,8
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![x^2+ax-9=(x+m)(x+n) m,n为正整数,则有自然数a的值?A.0,-8.8 B.正负8 C.0,-8 D.0,8](/uploads/image/z/3961797-69-7.jpg?t=x%5E2%2Bax-9%3D%28x%2Bm%29%28x%2Bn%29+m%2Cn%E4%B8%BA%E6%AD%A3%E6%95%B4%E6%95%B0%2C%E5%88%99%E6%9C%89%E8%87%AA%E7%84%B6%E6%95%B0a%E7%9A%84%E5%80%BC%3FA.0%2C-8.8+B.%E6%AD%A3%E8%B4%9F8+C.0%2C-8+D.0%2C8)
x^2+ax-9=(x+m)(x+n) m,n为正整数,则有自然数a的值?A.0,-8.8 B.正负8 C.0,-8 D.0,8
x^2+ax-9=(x+m)(x+n) m,n为正整数,则有自然数a的值?A.0,-8.8 B.正负8 C.0,-8 D.0,8
x^2+ax-9=(x+m)(x+n) m,n为正整数,则有自然数a的值?A.0,-8.8 B.正负8 C.0,-8 D.0,8
x^2+ax-9=(x+m)(x+n)=x^2+(m+n)x-mn
则
m+n=a
mn=-9=(-1)x9=1x(-9)=(-3)x3
故:a=m+n=8,-8,0