Take the sequence in 1a
The 10th term is 31
The 20th is 61
If you wanted to find these by continuing the series, you'd have to add 3 to the last number in the series, then 3 more, then 3 more, until you reach the 20th term. By this point, you will have added 3 to the first term 19 times. That's where the formula comes from. So here,
a = 4, the first term
n = 20, the number of the term we need
d = 3, how much we're adding each time between one term and the next
Then, to get the 20th term,
4 + (20 - 1) • 3 = 4 + (19 • 3) = 4 + 57 = 61
Answers
The 10th and 20th terms of each sequences are
a. 31; 61
b. 48; 98
c. 47; 97
(in <em>c</em>, you're adding the same <em>d</em> as in the sequence above, but your first term is one unit less)
d. -25; -75
(same thing as before, but now, <em>d</em> is negative)
e. 11.5; 16.5
(with <em>d</em>=1/2 or 0.5)
f. 6+1/2; 8+1/2
Use these to check your answers after applying the formula, but know that I calculated on the fly and didn't check these.
Answer:
f
(
x
)
=
3
x
3
−
5
x
2
−
47
x
−
15
Explanation:
If the zero is c, the factor is (x-c).
So for zeros of
−
3
,
−
1
3
,
5
, the factors are
(
x
+
3
)
(
x
+
1
3
)
(
x
−
5
)
Let's take a look at the factor
(
x
+
1
3
)
. Using the factor in this form will not result in integer coefficients because
1
3
is not an integer.
Move the
3
in front of the x and leave the
1
in place:
(
3
x
+
1
)
.
When set equal to zero and solved, both
(
x
+
1
3
)
=
0
and
(
3
x
+
1
)
=
0
result in
x
=
−
1
3
.
f
(
x
)
=
(
x
+
3
)
(
3
x
+
1
)
(
x
−
5
)
Multiply the first two factors.
f
(
x
)
=
(
3
x
2
+
10
x
+
3
)
(
x
−
5
)
Multiply/distribute again.
f
(
x
)
=
3
x
3
+
10
x
2
+
3
x
−
15
x
2
−
50
x
−
15
Combine like terms.
f
(
x
)
=
3
x
3
−
5
x
2
−
47
x
−
15
Let the number be x and 2x-5 from the above given condition
x+2x-5=70
or
3x=75 s0 x=25
Hence, the number are 25 and 45
Answer:
3 groups of 5 sopranos and 12 altos
Step-by-step explanation:
Answer:
d = 4/c.
Step-by-step explanation:
Inverse variation is : d = k/c where k is a constant.
Here k = 4.
