Answer:
Step-by-step explanation:
The Pascal triangle is used to determine the coefficients of the terms when we expand the expression.
1
= 1
1 1 
1 2 1 
By extending the triangle, you will get the 9th row, which is your expression, of the coefficients. that is
1 9 36 84 126 126 84 36 9 1
Now, fill in AB in the gaps.
1AB + 9 AB + 36AB + 84AB + 126AB + 126AB +84AB + 36AB + 9AB + 1AB
Next, you need to go from the left to fill out the exponent of A and it will go down from 9 (the exponent of the whole thing) . That is

Next will be the exponent of B. this time, you go from the right and do the same with A. You can go from the left also, but go up from 0 to 9 for the exponent of B

The last step is just to simplify the A^0=1 and B^0 =1 at the first and the last terms.

Hope you can learn the method
Answer:
C
Step-by-step explanation:
plug in the points for the equation on C and you'll get see that it fits
Answer:
the value of x=5 and y = -3
An x or a cross_____________
Since she has seven key the probability that the first one will open the door is

if it takes three attempts to open the door,the probability is

if the three attempts would not work
then the probability that the fourth attempt will open the door is

hope this helps