化简求值: (m-4)/(m^2-9)•{1+[(14m-7)/(m^2+8m+16)]}÷[1/(m-3) ] 其中m=5
问题描述:
化简求值: (m-4)/(m^2-9)•{1+[(14m-7)/(m^2+8m+16)]}÷[1/(m-3) ] 其中m=5
答
(m-4)/(m^2-9)•{1+[(14m-7)/(m^2+8m+16)]}÷[1/(m-3) ]
=(m-4)/(m+3)(m-3) × (m²+8m+16+14m-7)/(m+4)² ×(m-3)
=(m-4)/(m+3)× (m²+22m+9)/(m+4)²
=(5-4)/(5+3)×(25+110+9)/9²
=1/8×144/81
=2/9