Recall that

Dividing both sides by cosh²(x) gives

Also, recall the identity

Then

Step-by-step explanation:
4x² - 12x + 9 = 5 → 4x² - 12x + 4 = 0 → x² - 3x + 1 = 0
∆ = b² - 4ac → ∆ = (-3)² -4(1)(1) = 9 - 4 = 5
x = (-(-3) ± √5)/2(1) = (3 ± √5)/2
x² - 3x + 1 = 0 → (x - 3/2)² - 9/4 + 1 = 0 → (x - 3/2)² = 5/4 → x - 3/2 = ±√5 / 2 → x = ½( 3 ± √5)
Answer:
5 and 6
Step-by-step explanation:
call them a and b, respectively
we have a*b=30 -> a=30/b
a+b=11 -> b+ 30/b=11
b=6 and a=5