以知m=1/2 求代数式(m+2)2008次方乘以(2m-7/5)2009次方求求那些能人们

(m+2)^2008 * (2m-7/5)^2009
=(m+2)^2008 * (2m-7/5)^2008 * (2m-7/5) 把2009次方分割成2008和1次方
=[(m+2) * (2m-7/5)]^2008 * (2m-7/5) 两个2008次方的因式合并相乘
=[ 5/2 * (-2/5)]^2008 * (2*1/2 - 7/5) 代入m=1/2
=(-1)^2008 * (-2/5)
=-2/5

直接代入
（2.5)^2008×(-0.4)^2009
=(2.5)^2008×(-0.4)^2008×-0.4
=(2.5×-0.4)^2008×-0.4
=-1^2008×-0.4
=-0.4