**Answer:**

=
−
1
±√
5

**Step-by-step explanation:**

**Answer:**

I'm pretty sure it's D, sorry if I'm wrong

**Step-by-step explanation:**

**Answer:**

20

**Step-by-step explanation:**

Because this is a right triangle, you can use the Pythagorean Theorem, a^2 + b^2 = c^2. a and b are your legs and c is your hypotenuse, so you have 21^2 + b^2 = 29^2. This equals to 441 + b^2 = 841. subtract 441 from both sides and you are left with b^2 = 400. take the square root of both sides to get your answer b = 20, or** x = 20**.