Can someone help me please!!

Yes I can. So I will.

Step-by-step explanation:

Anytime you found yourself in doubt and danger about equations, you can use Geogebra Graph Calc - search for it -, and he will show you the graphic.

But, as I know that you are one the LAST HEROES IN EARTH, I pretty sure you don't want to just surrender yourself for a computer machine.

Let's calculate it:

4x² - 39x + 77

Bháskara Formula, you probably know her as Resolutive Formula, as she is known in my country, is:

there is also two signals + - betwen -b and the root.

She's one of the best ways to find roots for quadratic equations.

We will need to do that to find the interval required.

Also, remember that a generic quadratic equation can be describe as:

ax² + bx + c

So, knowing that in this equation

a = 4 / b = -39 / c = 77

We can proceed.

x' = - (-39) + / 2.4

x' = 39 + 17/ 8

x' = 7

x'' = 39 -17/8

x'' = 2,75

Now, you should know that when A > 0 the quadratic equation has her concavity facing down.

As we have the values of the roots, 7 and 2,75, we know that betwen them the equation has negative values.

That also means that all values higher than 7 and lower than 2,75 give to us a positive value.

Final

x<2,75 and x>7

You will see in annex the graphic.

the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

step-by-step explanation: