Answer:
23d + 45 = 137
Explanation:
Since it is $23 per day, that dollar amount must be associated with a variable that multiples it per day that it is rented. Finally, you need to add the one time $45. This equation can then be used to find how many days it was rented for.
23d + 45 = 137
23d = 92 (Subtract 45 from both sides)
d = 4 (Divide by 23 on both sides)
The rug-cleaning machine was rented for 4 days. You found this using the equation: 23d + 45 = 137
For
, on the left we have
, and on the right,

(where we use the double angle identity:
)
Suppose the relation holds for
:

Then for
, the left side is

So we want to show that

On the left side, we can combine the fractions:

Recall that

so that we can write




(another double angle identity:
)
Then recall that

which lets us consolidate the numerator to get what we wanted:

and the identity is established.
(5x^2 - 7)(5x^2 + 7)
(5x^2)^2 - 7^2
25x^4 - 49
Answer:
25x^4 - 49
Hope this helps.
21499 +12*x=22.75*x
21499=22.75x-12x
21499=10.75x
x=21499/10.75≈1999.9≈2000 books