Answer:
A
Step-by-step explanation:
We have the expression:

And we want to find its sign given that a>0 and b<0.
Notice that the expression is already negative since we have -4.
a>0 means that a is positive. Therefore, we can ignore it since it won’t do anything.
b<0 means that b is negative. Therefore, we will have two negatives being multiplied together. Hence, this will make a positive.
Therefore, the sign of our expression will be positive.
We can see this with an example. Let a=1 (1>0) and let b=-1 (-1<0). Then:

So, the sign is positive.
Hence, the answer is A.
Answer:
a = 36 and a = 27
Step-by-step explanation:
The geometric mean of two numbers is the square root of the product of the two numbers.
Say for example we have the numbers x and y, the geometric mean z is mathematically;
z = √xy
For the first question, our z is 12, x and y are 4 and a respectively.
12 = √4a
square both sides
144 = 4a
a = 144/4
a = 36
For the second question
z is 9, x and y are 3 and a respectively
9 = √3a
square both sides
81 = 3a
a = 81/3
a = 27
Answer: Plane AEF
Step-by-step explanation: Parallel means equal or same as. If you follow the letters BCD you can see that it sorta makes a triangle shape. So if you follow the answer choices you could see that AEF is the only one that does what BCD does if that makes sense :)
Answer:
2/12 + 3/12 + 3/12 + 2/12 + 5/12
Step-by-step explanation:
I hope I'm right