﹣5x²+ax+bx²+2x-5与x的取值无关,求a,b的值.思路写清楚 ,让我明白
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![﹣5x²+ax+bx²+2x-5与x的取值无关,求a,b的值.思路写清楚 ,让我明白](/uploads/image/z/9293019-51-9.jpg?t=%EF%B9%A35x%26%23178%3B%EF%BC%8Bax%EF%BC%8Bbx%26%23178%3B%EF%BC%8B2x%EF%BC%8D5%E4%B8%8Ex%E7%9A%84%E5%8F%96%E5%80%BC%E6%97%A0%E5%85%B3%2C%E6%B1%82a%2Cb%E7%9A%84%E5%80%BC.%E6%80%9D%E8%B7%AF%E5%86%99%E6%B8%85%E6%A5%9A+%2C%E8%AE%A9%E6%88%91%E6%98%8E%E7%99%BD)
﹣5x²+ax+bx²+2x-5与x的取值无关,求a,b的值.思路写清楚 ,让我明白
﹣5x²+ax+bx²+2x-5与x的取值无关,求a,b的值.思路写清楚 ,让我明白
﹣5x²+ax+bx²+2x-5与x的取值无关,求a,b的值.思路写清楚 ,让我明白
原式=(b-5)x²+(a+2)x-5
与x的取值无关则所有含x的想系数为0
所以b-5=0,a+2=0
所以a=-2,b=5
﹣5x²+ax+bx²+2x-5
= (-5+b)x^2 + (a+2)x -5
independent of x
=> coef. of x^2 and coef. of x =0
=> -5+b =0 and a+2=0
=> b=5 and a =-2