sarah is demonstrating the idea that polynomials are closed under addition her work and explanation are shown part a add 3x^4+6x-7 to a 2x^3-(2x)^2+4x^-1 b (2x)^2+4.4x-9 x(-8x)^-2 -(3x)^3+7 part b is in the picture

Anyone know? will mark brainliest if correct

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?

In a right triangle δabc, the length of leg ac = 5 ft and the hypotenuse ab = 13 ft. find: b the length of the angle bisector of angle ∠a.