Answer: A. A(1) = 14; A(n) = (n − 1) −4; A(n) = 14 + (n − 1)(−4)
Step-by-step explanation:
Arithmetic sequence is a sequence that is identified by their common difference. Let a be the first term, n be the number of terms and d be the common difference.
For an arithmetic sequence, common difference 'd' is added to the preceding term to get its succeeding term. For example if a is the first term of a sequence, second term will be a+d, third term will give a+d+d and so on to generate sequence of the form,
a, a+d, a+3d, a+4d...
Notice that each new term keep increasing by a common difference 'd'
The nth term of the sequence Tn will therefore give Tn = a+(n-1)d
If the initial (first) term is 14 and common difference is -4, the nth of the sequence will be gotten by substituting a = 14 and d = -4 in the general formula to give;
Tn = 14+(n-1)-4 (which gives the required answer)
Tn = 14-4n+4
Tn = 18-4n
14C3 = 14! / 11!3!
<span>= 14 x13 x12 / 3x2x1 </span>
<span>= 2184 / 6 </span>
<span>= 364 different combinations </span>
<span>The first movie can be any of 14 </span>
<span>As you have already seen one the second movie can be any of the 13 remaining </span>
<span>As you have already seen two the third movie can be any of the 12 remaining. </span>
<span>Therefore there are 14 x 13 x 12 = 2184 PERMUTATIONS of movies you can see. </span>
<span>However among those 2184 different permutations will be instances where you have watched the same three movies but just in a different order. </span>
<span>eg ET, The Piano, Harry Potter = ET Harry Potter The Piano = The Piano, ET, Harry Potter = The Piano Harry Potter ET = Harry Potter ET The Piano = Harry Potter The Piano ET. </span>
<span>For each set of three films there are 3! or 3x2x1 or SIX different ways they can be arranged in. </span>
<span>Therefore we need to DIVIDE the above 2184 permutations by 6 to get the number of COMBINATIONS of different films that can be watched. </span>
<span>2184 / 6 = 364</span>
It could be D or C
The system has two solutions
x = .8 y = .6
OR if you think about it , (x=.8 y=.6) could be considered THE solution.
I would go with choice C