作业帮22.先化简,再求值:[(3a-7)²-(a+5)²]/(4a-24),其中a=1/50
来源：学生作业帮助网 编辑：作业帮 时间：2024/04/29 15:17:53
![22.先化简,再求值:[(3a-7)²-(a+5)²]/(4a-24),其中a=1/50](/uploads/image/z/758141-53-1.jpg?t=22.%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%3A%5B%283a-7%29%26%23178%3B-%28a%2B5%29%26%23178%3B%5D%2F%284a-24%29%2C%E5%85%B6%E4%B8%ADa%3D1%2F50)
22.先化简,再求值:[(3a-7)²-(a+5)²]/(4a-24),其中a=1/50
22.先化简,再求值:[(3a-7)²-(a+5)²]/(4a-24),其中a=1/50
22.先化简,再求值:[(3a-7)²-(a+5)²]/(4a-24),其中a=1/50
[(3a-7)^2-(a+5)^2]/(4a-24)
=[(9a²-42a+49)-(a²+10a+25)]/(4a-24)
=(8a²-52a+24)/[4(a-6)]
=(a-6)(8a-4)/[4(a-6)]
=(8a-4)/4
=2a-1
=2*(1/50)-1
=1/25-1
=-24/25