Is 21 km, 28 km, 35 km, a right triangle

1. C. Yes, because a sum of cubes can be factored

2a. false

2b. false

2c. true

2d. false (based on what is written in the equation; refer to step-by-step)

Step-by-step explanation:

1.  Both 3 and 8 can be cubed, which is why x^3+8 can be factored (x+2)(x^2-2x+4)

2a. a^2-b^2 can be factored by the perfect square rule, so it should be (a-b)^2

2b. both terms are perfect squares, so you can factor, making it (a+b)(a-b)

2c. You can factor using the perfect square rule, making it (a+b)^2

2d. Most of what is in the equation is true, yet the correct solution would be (a-b)(a^2+ab+b^2)