One-third of a number......1/3n
increased by 12....+ 12
(1/3)n + 12
Start by looking at the vertex form of a quadratic function, f(x) = a(x - h)^2 + k. The variables h and k are the values of the vertex. Plug those in to get f(x) = a(x - 4)^2 + 5. To find the variable a, plug in the point given for the x and y values. So, you get (21) = a((8) - 4)^2 + 5. Solve for a algebraically, and you get a = 1. Finally, plug everything in and simplify the equation. You should get that the quadratic function is f(x) = x^2 - 8x + 21. Hope this helps!
You have to get a variable by itself like in here... Y is itself so in the other equation or we can say second one you just have to sub it in... Like
2x+5(-3x-2)=16
2x-15x-10=16
Now you just have to subtract 2 from 15, because of the same variable that is (x)
So -13x-10=16
Take 10 to the other side means add from the both sides, that will get you at
-13x=26
So now x= -2
Remember you added because it was -10 if it would be a positive 10 then you have to subtract it from both of the sides but since here it was negative so you just added them up
Hope i helped