Answer:
8 ejercicios
Step-by-step explanation:
De acuerdo a la información dada, puedes plantear las siguientes ecuaciones:
x+y= 45 (1)
7x-1y= 19 (2)
x= ejercicios que resolvió bien
y= ejercicios que resolvió mal
Primero, puedes despejar x en (1):
x= 45-y (3)
Segundo, debes reemplazar (3) en (2):
7(45-y)-1y=19
315-7y-1y= 19
315-8y= 19
315-19= 8y
296= 8y
y= 296/8
y= 37
Tercero, debes reemplazar el valor de y en (3) para encontrar x:
x= 45-37
x= 8
De acuerdo a esto, la respuesta es que el hijo ha resuelto bien 8 ejercicios.
EG is 12.2 because the line down the middle is called a bisect which means that it splits the triangle right down the middle making each side equal. so if you do 6.1 x 2 or just add 6.1+6.1 which is the same thing lol, you will have your answer
Answer:
Ok, we have a system of equations:
6*x + 3*y = 6*x*y
2*x + 4*y = 5*x*y
First, we want to isolate one of the variables,
As we have almost the same expression (x*y) in the right side of both equations, we can see the quotient between the two equations:
(6*x + 3*y)/(2*x + 4*y) = 6/5
now we isolate one off the variables:
6*x + 3*y = (6/5)*(2*x + 4*y) = (12/5)*x + (24/5)*y
x*(6 - 12/5) = y*(24/5 - 3)
x = y*(24/5 - 3)/(6 - 12/5) = 0.5*y
Now we can replace it in the first equation:
6*x + 3*y = 6*x*y
6*(0.5*y) + 3*y = 6*(0.5*y)*y
3*y + 3*y = 3*y^2
3*y^2 - 6*y = 0
Now we can find the solutions of that quadratic equation as:

So we have two solutions
y = 0
y = 2.
Suppose that we select the solution y = 0
Then, using one of the equations we can find the value of x:
2*x + 4*0 = 5*x*0
2*x = 0
x = 0
(0, 0) is a solution
if we select the other solution, y = 2.
2*x + 4*2 = 5*x*2
2*x + 8 = 10*x
8 = (10 - 2)*x = 8x
x = 1.
(1, 2) is other solution