Question

Ajutoooor!Dau coroană!!!​

Answer 1

Răspuns:

Explicație pas cu pas:

A_______B__________C_____D

AD/AB + BC/CD = (1/AB + 1/CD)*BD

AD/AB + BC/CD = (AB + BD)/AB + (BD - CD)/CD = AB/AB + BD/AB + BD/CD - CD/CD = 1 + BD/AB + BD/CD - 1 = BD/AB + BD/CD = (1/AB + 1/CD)*BD

Answer 2

$\it \dfrac{AD}{AB}+\dfrac{BC}{CD}=\dfrac{AB+BD}{AB}+\dfrac{BD-CD}{CD} =\dfrac{AB}{AB}+\dfrac{BD}{AB}+\dfrac{BD}{CD}-\dfrac{CD}{CD} = \\ \\ \\ =1+\dfrac{BD}{AB}+\dfrac{BD}{CD} -1 =\dfrac{BD}{AB}+\dfrac{BD}{CD}=\Big(\dfrac{1}{AB} +\dfrac{1}{CD} \Big)\cdot BD$