12. Describe the triangles formed by the diagonals of these
quadrilaterals.
a) isosceles trapezoid
b) parallelogram
c) square

a) An isosceles trapezoid is a trapezoid in which the base angles are equal and therefore the left and right side length are also equal.

b) A quadrilateral having it's opposite side equal and parallel is parallelogram.

c) Square is regular quadrilateral which means that it has four equal sides and four equal angles.

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!