姐姐,再帮我一个忙 已知A=2a²-a,B=-5a+1,B=-5a+1 (1)化简:4A-2B-1 (2)当a=-1时,求4A-2B-1的值
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![姐姐,再帮我一个忙 已知A=2a²-a,B=-5a+1,B=-5a+1 (1)化简:4A-2B-1 (2)当a=-1时,求4A-2B-1的值](/uploads/image/z/659621-29-1.jpg?t=%E5%A7%90%E5%A7%90%2C%E5%86%8D%E5%B8%AE%E6%88%91%E4%B8%80%E4%B8%AA%E5%BF%99+%E5%B7%B2%E7%9F%A5A%3D2a%26%23178%3B-a%2CB%3D-5a%2B1%2CB%3D-5a%2B1+%EF%BC%881%EF%BC%89%E5%8C%96%E7%AE%80%EF%BC%9A4A-2B-1+%282%29%E5%BD%93a%3D-1%E6%97%B6%2C%E6%B1%824A-2B-1%E7%9A%84%E5%80%BC)
姐姐,再帮我一个忙 已知A=2a²-a,B=-5a+1,B=-5a+1 (1)化简:4A-2B-1 (2)当a=-1时,求4A-2B-1的值
姐姐,再帮我一个忙 已知A=2a²-a,B=-5a+1,B=-5a+1 (1)化简:4A-2B-1 (2)当a=-1时,求4A-2B-1的值
姐姐,再帮我一个忙 已知A=2a²-a,B=-5a+1,B=-5a+1 (1)化简:4A-2B-1 (2)当a=-1时,求4A-2B-1的值
(1)化简:4A-2B-1 =4(2a²-a)-2(-5a+1)=8a²-4a+10a-2=8a²+6a-2
(2)当a=-1时,4A-2B-1=8a²+6a-2=8-6-2=0
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