A geometric sequence is a sequence in which there is a common ratio between any two consecutive terms. In this case if X:Y:Z are in the ratio of 2:7:8 the multiplying by a constant k, we have X=2k, Y= 7k and Z=8k.
Then if X, Y-12, Z form a Geometric sequence, it means X/Y-12=Y-12/Z which is the same as 2k/7k-12=7k-12/8k if we cross multply, we get
16k²= 49k²-168k +144
33k²-168k+144 =0 solving for k
k = 4 or 1.091 if we take the whole number to find the values of X,Y and z,
X= 8, Y= 28 and Z=32
The answer is: " 9a² + 7a " .
_________________________________
Note: (3a)² + 7a = (3a)*(3a) + 7a = 9a² + 7a .
_________________________________
While it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton. In fact, the opposite occurred. Cotton growing became so profitable for the planters that it greatly increased their demand for both land and slave labor
Answer:
a = 1.5
b = 1.75
Step-by-step explanation:
First, we need to solve 
and replace the result in the initial equation as:
Then, this equality apply only if the coefficient of 
is equal in both sides and the constant is equal in both sides.
It means that we have two equations:
So, using the first equation and solving for a, we get:
Finally, replacing the value of a in the second equation and solving for b, we get:
