Answer:the cost of renting one movie is $1.5
the cost of renting one video game is $5.2
Step-by-step explanation:
Let x represent the cost of renting one movie.
Let y represent the cost of renting one video game. One month melissa rented 12 movies and 2 video games for a total of $29. This means that
12x + 2y = 29 - - - - - - -1
The next month she rented 3 movies and 5 video games for a total of 32$. This means that
3x + 5y = 32 - - - - - - - - 2
Multiplying equation 1 by 5 and equation 2 by 2, it becomes
60x + 10y = 145
6x + 10y = 64
Subtracting,
54x = 81
x = 81/54 = 1.5
Substituting x = 1.5 into equation 2, it becomes
3x + 5y = 32
3×2 + 5y = 32
5y = 32 - 6 = 26
y = 26/5 = 5.2
Step-by-step explanation:
(a²-b²)(c²-d²) = a²c² - a²d² - b²c² + b²d²
(b²-d²)(c²-a²) = b²c² - a²b² - c²d² + a²d²
the sum of both is
a²c² + b²d² - a²b² - c²d² = a²(c²-b²) + d²(b²-c²) =
= a²(c²-b²) - d²(c²-b²) = (c²-b²)(a²-d²) = 2021
after a little check we find 2021 is only divisible by 43 and 47 (or 1 and 2021).
so, it is clear that our expression resembles
43×47 = 2021
that means that e.g. c²-b² = 43, and a²-d² = 47
or the other way around, it does not matter.
what squared integer numbers give a difference of 43 ? and 47 ?
squared numbers
1 4 9 16 25 36 49 64 81 100 121 144 169 196 225 256
289 324 361 400 441 484 529 576
aha ! 484 - 441 = 43
and 576 - 529 = 47
so, we get
a = sqrt(576) = 24
b = sqrt(441) = 21
c = sqrt(484) = 22
d = sqrt(529) = 23
one could also use the formula for consecutive squared numbers
(n+1)² = n² + 2n + 1
under the assumption that the 2 numbers are convective (which it turns out they are in this example) we get
(n+1)² - n² = 2n + 1 = 43
2n = 42
n = 21
n+1 = 22
and for 47
2n + 1 = 47
2n = 46
n = 23
n+1 = 24
Answer:
(0,−2)
Step-by-step explanation:
