Question

无论ab取任何有理数,都有五分之四a立方b的n+2方+(m-1)a的立方b的四次方=0成立试求代数式（m的平方-2mn-

Answer 1

4/5a³b^(n+2)+(m-1)a³b^4=0

4/5a³b^(n+2)=-(m-1)a³b^4

4/5b^(n+2)=(1-m)b^4

4/5=1-m m=1/5

n+2=4 n=2

m²-2mn-3n=(1/5)²-2(1/5)*2-3*2

=1/25-4/5-6

=(1-20-6*25)/25

=-169/25