x
=
−
7
or
x
=
−
8
Explanation:
Find a pair of factors of
56
with sum
15
.
The pair
7
,
8
works in that
7
⋅
8
=
56
and
7
+
8
=
15
Hence:
0
=
x
2
+
15
x
+
56
=
(
x
+
7
)
(
x
+
8
)
So:
x
=
−
7
or
x
=
−
8
Alternative method
Or, using the definition of the derivative,
Answer:
Length = 4 feet
Width = 4 feet
Step-by-step explanation:
The perimeter of a rectangle formula = 2L + 2W
Where L = Length
W = Width
The length of a rectangle is 8feet less than the width.
Hence,
L = 8 - W
The perimeter is 64 feet.
Hence,
64 = 2(8 - W) × 2W
64 =( 16 - 2W )2W
64 = -4W² + 32W
4W² - 32W + 64 = 0
Factorise
4W² - 16W - 16W + 64 = 0
4W (W - 4) - 16(W - 4) = 0
W - 4 = 0
W = 4
Width = 4
Solving for L
L = 8 - W
L = 8 - 4
L = 4
Therefore,
Length = 4 feet
Width = 4 feet
$19.95x +$3
x stands for number of tickets purchased.
$19.95(5) + $3
$99.75 + $3
$102.75 for 5 tickets