Which of the following equations have exactly one solution?
Choose all answers that apply:
A 2x - 31 = 2x – 31
B 2x - 31 = -2x – 31
C 2x + 31 = 2x - 31
D 2x - 2 = 20 – 31

What is the value of the expression 9+n/3-6 when n = 12? 1. 5. 7. 12.

[15 points]find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible

Prove (a) cosh2(x) − sinh2(x) = 1 and (b) 1 − tanh 2(x) = sech 2(x). solution (a) cosh2(x) − sinh2(x) = ex + e−x 2 2 − 2 = e2x + 2 + e−2x 4 − = 4 = . (b) we start with the identity proved in part (a): cosh2(x) − sinh2(x) = 1. if we divide both sides by cosh2(x), we get 1 − sinh2(x) cosh2(x) = 1 or 1 − tanh 2(x) = .