(ax²-3x+by-1)-2(3-y-3/2x+x²)中,无论x、y取任何有理数,多项式的值都不变,求:4(a²-ab+b²)-3(2a²+b²+5)的值.急求!
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![(ax²-3x+by-1)-2(3-y-3/2x+x²)中,无论x、y取任何有理数,多项式的值都不变,求:4(a²-ab+b²)-3(2a²+b²+5)的值.急求!](/uploads/image/z/814818-66-8.jpg?t=%EF%BC%88ax%26%23178%3B-3x%2Bby-1%EF%BC%89-2%EF%BC%883-y-3%2F2x%2Bx%26%23178%3B%EF%BC%89%E4%B8%AD%2C%E6%97%A0%E8%AE%BAx%E3%80%81y%E5%8F%96%E4%BB%BB%E4%BD%95%E6%9C%89%E7%90%86%E6%95%B0%2C%E5%A4%9A%E9%A1%B9%E5%BC%8F%E7%9A%84%E5%80%BC%E9%83%BD%E4%B8%8D%E5%8F%98%2C%E6%B1%82%EF%BC%9A4%EF%BC%88a%26%23178%3B-ab%2Bb%26%23178%3B%EF%BC%89-3%EF%BC%882a%26%23178%3B%2Bb%26%23178%3B%2B5%EF%BC%89%E7%9A%84%E5%80%BC.%E6%80%A5%E6%B1%82%21)
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(ax²-3x+by-1)-2(3-y-3/2x+x²)中,无论x、y取任何有理数,多项式的值都不变,求:4(a²-ab+b²)-3(2a²+b²+5)的值.急求!
(ax²-3x+by-1)-2(3-y-3/2x+x²)中,无论x、y取任何有理数,多项式的值都不变,求:
4(a²-ab+b²)-3(2a²+b²+5)的值.
急求!
(ax²-3x+by-1)-2(3-y-3/2x+x²)中,无论x、y取任何有理数,多项式的值都不变,求:4(a²-ab+b²)-3(2a²+b²+5)的值.急求!
(ax²-3x+by-1)-2(3-y-3/2x+x²)
=ax²-3x+by-1-6+2y+3x-2x²
=(a-2)x²+(b+2)y-7
无论x、y取任何有理数,多项式的值都不变,所以a=2,b=-2
所以 4(a²-ab+b²)-3(2a²+b²+5)=-2a²-4ab+b²-15=-8+16+4-15= -3