Edgar earns $13 for each hour of yard work. How many hours in all will it take Edgar to earn $39? hours​

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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) = .

26) -2(7x) = (-2 • 7) x a. associative property of addition b. associative property of multiplication c. commutative property of multiplication d. commutative property of addition