m^2-3m+6是否大于0

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m^2-3m+6是否大于0
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m^2-3m+6是否大于0
m^2-3m+6是否大于0

m^2-3m+6是否大于0
用配方法:m^2-3m+6=m^2-3m+9/4-9/4+6=(m-3/2)^2+15/4
因为(m-3/2)^2大于等于0,所以(m-3/2)^2+15/4>0.

首先配方,得(m-3/2)^2+15/4,而(m-3/2)^2>=0,则m^2-3m+6>=15/4,大于0

  • m^2-3m+6=m^2-3m+9/4+15/4=(m+3/2)^2+15/4>0

a为1,b为-3,c为6,b∧2-4ac<0,a>o所以此式恒大于0

m²-3m+6=(m-3/2)²+(15/4);
∵(m-3/2)²>0;
∴m²-3m+6>0;

m²-3m+6
=m²-3m+(3/2)²-(3/2)²+6
=(m-3/2)²+15/4
因不论m取何值都有:(m-3/2)²≥0
即:(m-3/2)²+15/4>0
所以可得:
m²-3m+6>0

m^2-3m+6=[m-(3/2)]^2+6-(9/4)
=[m-(3/2)]^2+(15/4)
∵[m-(3/2)]^2≥0
∴[m-(3/2)]^2+(15/4)≥15/4
∴m^2-3m+6>0