Помогите с задачкой !

1) 1/7*49+1/2*1/4=7+1/8=7+0,125=7,125
 2) а...12а⁴вх⁵у⁴/15а²в³х⁶у⁴= 4а²/5в²х
     б...а²в
3) ((m-n)(m¹/²+n¹/²)-(m³/²-n³/²))/(m-n)= (m³/²-nm¹/²+mn¹/²-n³/²-m³/²+n³/²)/(m-n)=(mn¹/²-nm¹/²)/(m-n)=m¹/²n¹/²(m¹/²-n¹/²)/(m-n)=(mn)¹/²:(m¹/²-n¹/²)=√mn/(√m-√n)