Which is an irrational number option 1 square root of 21 option 2 3 and 5/8 option 3 2.4141414 option 4 -13 plz I need this answer

Here is their argument. given the obtuse angle x, we make a quadrilateral abcd with ∠dab = x, and ∠abc = 90◦, and ad = bc. say the perpendicular bisector to dc meets the perpendicular bisector to ab at p. then pa = pb and pc = pd. so the triangles pad and pbc have equal sides and are congruent. thus ∠pad = ∠pbc. but pab is isosceles, hence ∠pab = ∠pba. subtracting, gives x = ∠pad−∠pab = ∠pbc −∠pba = 90◦. this is a preposterous conclusion – just where is the mistake in the "proof" and why does the argument break down there?

Find the greatest common factor of -30x 4 yz 3 and 75x 4 z 2.

This question awards 100 ! i really don’t want to fail i will also mark you !