For these kinds of expressions use FOIL (first, outside, inside, last).
-2x • 9x = -18x^2
-2x • -3y = 6xy
8y • 9x = 72 xy
8y • -3y = -24y^2
Now combine them all:
-18x^2 + 78xy - 24y^2
Answer: I would choose option 3 for the 9th question
Step-by-step explanation:
1). Download "Photomath" XD
-- If the 55° angle is one of the two equal angles, then
the third angle is 70° .
-- If the 55° angle is the third angle, then each of the two
equal angles is 62.5° .
-- For either of these cases, there are an infinite number
of possible sets of side-lengths.
The statement in the question does not hold water.