To find a missing side of a right triangle use the Pythagorean theorem
A2+b2=c2
C is the hypotenuse (long side)
Plug into the equation
11^2+b2=12^2
121+b2=144
So subtract 144-121 to get the missing side you get 23
Take the square root
It will be 4.7
If they want it rounded
X=5
If I had any mistakes in my answer I am sorry but everything should be correct

To solve this equation , we need to write it in quadratic form

To get the equation in quadratic form we replace x^2 with u

can be written as
, Replace u for x^2
So equation becomes

Now we factor the left hand side
-16 and -1 are the two factors whose product is +16 and sum is -17
(u-16) (u-1) = 0
u -16 = 0 so u=16
u-1 =0 so u=1
WE assume u = x^2, Now we replace u with x^2
Now take square root on both sides , x= +4 and x=-4
Now take square root on both sides , x= +1 and x=-1
So zeros of the function are -4, -1, 1, 4
F(3k)=3k +7 Equals 9k+7. So 9k+7 would be the Answer.