explanation:
I would use V=4/3•3.14•r^3 to find the volume of a baseball .
Answer:
There were 30 children and 10 adults.
Step-by-step explanation:
Since they sold tickets to adults and childrens, the sum of those tickets must be equal to the total tickets that were sold, so we can mount our first equation as shown below:
adult + children = 40
Each adult ticket costs $9 and each children costs $5 and the total recieved was $240, therefore:
9*adult + 5*children = 240
We can mount the following equation system:
adult + children = 40
9*adult + 5*children = 240
We will multiply the first equation by -5 and sum both equations:
-5*adult -5*children = -200
9*adult + 5*children = 240
4*adult = 40
adult = 40 / 4
adult = 10
adult + children = 40
children = 40 - adult = 40 - 10 = 30
There were 30 children and 10 adults.
Answer:
El primer paso será darle un nombre a nuestras variables:
x= Numero de libros comprados inicialmente
y=Precio inicial de los libros
Ahora analizamos el enunciado,
Lorena ha comprado libros todos del mismo precio por valor de 120 €
x*y=120 € (1)
El librero le regala 3 libros por lo que en realidad cada libro que cuesta 2 € menos
(x+3)(y-2)=120€ (2)
Tenemos entonces dos ecuaciones con dos incógnitas, así que podemos resolver,
Despejamos en (1)
x=120/y
Sustituimos en (2)
(120/y +3)(y-2)=120
120 - 240/y + 3y -6 =120
3y-240/y =120-120+6
3y -240/y =6
y- 80/y=6
y²-80=6y
y²-6y-80=0
Resolvemos la ecuación de segundo grado
a=1
b=-6
c=-80
Aplicando la resolvente,
(6+- √36+320)/2
6+-√356/2
(6+-18,86)/2
Como el valor de y no puede ser negativo la unica respuesta válida será:
y=12,43
Cada libro le costo 12,43€
Sustituyendo en (1)
x=120/12,43
x=9,65 como no puede ser un número racional
x=9
Lorena ha comprado 9 libros
Answer:
x = -3
y = 7
Step-by-step explanation:
x + 3y = 18
-3x - 12y = -75
multiply first equation by 4
4 × (x + 3y) = 18 ➡ 4x + 12y = 72
now add the two equations up
4x + 12y - 3x -12y = 72 - 75 (-12y will eliminate 12y)
x = -3
