12S²t-20st² 2a四次方-6a³-2a² 什么的还有已知mn=﹣3,m-n=5,求代数式2m²n-2mn²的值
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![12S²t-20st² 2a四次方-6a³-2a² 什么的还有已知mn=﹣3,m-n=5,求代数式2m²n-2mn²的值](/uploads/image/z/8661984-24-4.jpg?t=12S%26%23178%3Bt%EF%BC%8D20st%26%23178%3B+2a%E5%9B%9B%E6%AC%A1%E6%96%B9-6a%26%23179%3B-2a%26%23178%3B+%E4%BB%80%E4%B9%88%E7%9A%84%E8%BF%98%E6%9C%89%E5%B7%B2%E7%9F%A5mn%3D%EF%B9%A33%2Cm-n%3D5%2C%E6%B1%82%E4%BB%A3%E6%95%B0%E5%BC%8F2m%26%23178%3Bn-2mn%26%23178%3B%E7%9A%84%E5%80%BC)
12S²t-20st² 2a四次方-6a³-2a² 什么的还有已知mn=﹣3,m-n=5,求代数式2m²n-2mn²的值
12S²t-20st² 2a四次方-6a³-2a² 什么的
还有已知mn=﹣3,m-n=5,求代数式2m²n-2mn²的值
12S²t-20st² 2a四次方-6a³-2a² 什么的还有已知mn=﹣3,m-n=5,求代数式2m²n-2mn²的值
12S²t-20st²
=4st(3s-5t)
2a四次方-6a³-2a²
=2a^2(a^2-3a-1)
已知mn=﹣3,m-n=5,
2m²n-2mn²
=2mn(m-n)
=2*(-3)*5
=-30