Which rational expression is undefined when a = 1? 6a²-6/7a+7
8a2/5a-10
10 a + 6/- a²+1
9a-3/3a²

Olivia uses the work below to determine 55% of 720 which explains the error in olivia’s solution

65 8 7 4 5 6 8 4 3 2 1 9 5 6 4 2 1 6 5 1 5 1 3 2 3 5 multiply the third number in the first row by the seventh number in the third row. add this result to the fifth number in the second row. add to this total ten times the fourth number in the third row. subtract the eighth number in the first row from the result.

Rhombus adef is inscribed into a triangle abc so that they share angle a and the vertex e lies on the side bc . what is the length of the side of the rhombus if ab=c, and ac=b.