f(x)=x^2+12x+26
Vertex form of f(x) = a(x-h)^2 +k
We change f(x) into vertex form using completing the square method

We take half of square of middle term
middle term is 12
Half of square of 12 is
then 6^2 = 36
Add and subtract 36 to complete the square


The vertex form 
I don't believe your expression is correct as is; it should be <span>100(1 + 0.4)^h.
You have not shared the possible answer choices; please do so.
</span>
Answer:
x=1
Step-by-step explanation:
-3x(5-4)+3(x-6)
-15x+12x+3x-18
-3x+3x-18
-18=-12x-6
-12x=-18+6
-12x=-12
12x=12
x=12/12
x=1
I'm pretty sure the answer will be 6/10
Hope this helps, best of luck, terribly sorry if I'm wrong if I am my apologies
~Animaljamissofab ♥