算术题 (18 20:24:23) 先化简,再求值.(t+3t2-3)-(-t=42),其中t=-12(3ab-1分之2a2)+a2-(3ab-b2),其中a=-2,b=1 &
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![算术题 (18 20:24:23) 先化简,再求值.(t+3t2-3)-(-t=42),其中t=-12(3ab-1分之2a2)+a2-(3ab-b2),其中a=-2,b=1 &](/uploads/image/z/699323-59-3.jpg?t=%E7%AE%97%E6%9C%AF%E9%A2%98+%2818+20%3A24%3A23%29%26%23160%3B%26%23160%3B%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC.%EF%BC%88t%2B3t2%EF%BC%8D3%EF%BC%89%EF%BC%8D%EF%BC%88%EF%BC%8Dt%3D42%EF%BC%89%2C%E5%85%B6%E4%B8%ADt%3D%EF%BC%8D12%EF%BC%883ab%EF%BC%8D1%E5%88%86%E4%B9%8B2a2%EF%BC%89%2Ba2%EF%BC%8D%EF%BC%883ab%EF%BC%8Db2%EF%BC%89%2C%E5%85%B6%E4%B8%ADa%3D%EF%BC%8D2%2Cb%3D1%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26%23160%3B%26)
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算术题 (18 20:24:23) 先化简,再求值.(t+3t2-3)-(-t=42),其中t=-12(3ab-1分之2a2)+a2-(3ab-b2),其中a=-2,b=1 &
算术题 (18 20:24:23)
先化简,再求值.
(t+3t2-3)-(-t=42),其中t=-1
2(3ab-1分之2a2)+a2-(3ab-b2),其中a=-2,b=1
算术题 (18 20:24:23) 先化简,再求值.(t+3t2-3)-(-t=42),其中t=-12(3ab-1分之2a2)+a2-(3ab-b2),其中a=-2,b=1 &
a2是不是a² 如果是的话,应打成 a^2.
(-t=42)是不是(-t-42)?
(t+3t2-3)-(-t-42),其中t=-1
=t+3t²-3+t+42
=3t²+2t-39
=3(-1)²+2(-1)-39
=3-2-39
=-38
2(3ab-1分之2a2)+a2-(3ab-b2),其中a=-2,b=1
=3ab-2a²+a²-3ab+b²
=b²-a²
=(b+a)(b-a)
=(1+(-2))(1-(-2))
=(-1)(+3)
=-3