Answer:
C) 
Step-by-step explanation:
By the cos double angle formula, we know
Substituting
into the formula, we get
.
The answer is C.
Answer:
xy+2x+3y+6=xy-5 .............(1)
xy-3x+2y-6=xy.....,.,(2)
2x+3y=-11
-4x+2y=6
first equation multiply by 2
(2)*(2x+3y)=-11
4x+6y=-22
-4x+2y=6
8y=-16 y=(-2),,,,, x=(-2,5)
Change the function into vertex form:
f(x)=x²-10x+16
make a square by (adding half of -10)², which is 25, then subtract it:
f(x)=x²-10x+25-25+16
f(x)=(x-5)²-9
so the vertex is at (5,-9)
another way to do it:
f(x)=x²-10x+16
the vertex is when x=-

, b=-10, a=1 in this case.
x=-(-10/2*1)=5
plug x=5 into the quadratic function, you get f(x)=-9
Answer:
The letters I and S are more likely to come out of the bag because they are repeated twice in the word.