2m-4分之m-3除以(m-2分之5减m-2)
=(m-3)/2(m-2)÷[5/(m-2)-(m+2)(m-2)/(m-2)]
=(m-3)/2(m-2)×(m-2)/(3+m)(3-m)
=-1/2(m+3)
当m=√2-3时
原式=-1/2√2
=-√2/4