Hello,
which principle?
f(x)=-x²+2x
==>f'(x)= -2x+2
You mean maybe this

f(x+h)=-(x+h)²+2(x+h)= -(x²+2hx+h²)+2x+2h
f(x)=-x²+2x
16 n^2 -10n + 129 = 8n^2 -8
We collect the terms:
8n^2 -10n + 137 = 0
The steps for completing the square:
1) Move the "non X" (or "non N") term to the right:
8n^2 -10n = -137
<span>2)<span> Divide the equation by the coefficient of N² which in this case is 8
n^2 -1.2n = </span></span><span><span>-17.125
</span>
3) Take the coefficient of "N"; divide it by 2; square it; add it to both sides of the equation.
-1.2 / 2 = -.6
-.6^2 = .36
</span>
n^2 -1.2n +.36 = <span>-17.125
+.36
Take the square root of both sides:</span>
(n-.6)*(n-.6) = sq root(
<span>
<span>
<span>
-16.765
</span>
</span>
</span>
)
That's about as far as I can go.
T1 + t2 = 2h and 30min;
t1 * 600 = t2 * 400 => t2 = (3/2) * t1;
then, t1 + (3/2) * t1 = 2h and 30min => 2t1 + 3t1 = 5h => 5*t1 = 5h => t1 = 1h => t2 = 1h and 30 min;
The distance is 2 * 1 * 600 = 1200miles;
The cosine ratio is adjacent leg divided by the hypotenuse.
The hypotenuse in a right triangle is the longest side and it is opposite the right angle.
An adjacent leg is the side that has an endpoint that is at the vertex of the angle and the other endpoint is at the vertex of the right angle.
cos A =

ANSWER: