Find y when x=9 if y varies directly as x, and y=245 when x=7
1 answer:
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Answer:
4
Step-by-step explanation:
If two variables are proportional then
...(i)
where, k is constant of proportionality.
The given equation is
...(ii)
where,
s = number of cups of seltzer.
c = cups of cranberry juice.
On comparing (i) and (ii), we get
Independent variable:
Dependent variable:
Constant of proportionality:
Therefore, the constant of proportionality is 4.
Answer:
Substitution and graphing are less efficient methods than elimination for this system as there is extra amount of steps we have to take to solve the same system of equations - hence time consuming and a margin or error may happen. Therefore, elimination is the suitable method for solving this system.
Step-by-step explanation:
Let us consider the system of equation below.
Elimination method sounds the most appropriate option to solve the given system of equations as we can easily sort out an equation in one variable x in minimal steps by just adding the both equations as the y-coefficient in the first equation is the opposite of the y-coefficient in the second equation, and we can determine an equation in one variable x.
Adding both equations will eliminate the y-variable and we can easily sort out the value of x from the resulting equation.
As the given system of equation
Adding Equation 1 and Equation 2
Putting in Equation [1]
Although substitution or graphing methods can also be used to bring the solution of the given system of equations, but using substitution or graphing method can be sometimes cumbersome or time-consuming as it would have to take some additional steps to solve the system.
For example, if we would have to use the substitution methods to solve the given system of equations, first we would have to solve one of the equations by choosing one of the equation for one of the chosen variables and then putting this back into the other equation, and solve for the other, and then back-solving for the first variable.
As the given system of equation
Solving the equation 2 for x variable
Plugging in equation [1]
Putting in Equation 2
So, you can figure out, we have to make additional steps when we use substitution method to solve this system of equations.
Similarly, using graphing method, it would take a certain time before we identify the solution of the system.
Hence, from all the discussion and analysis we did, we can safely say that substitution and graphing are less efficient methods than elimination for this system as there is extra amount of steps we have to take to solve the same system of equations - hence time consuming and a margin or error may happen.
Therefore, we agree with the student argument that Elimination is the best method for solving this system because the y-coefficient in the first equation is the opposite of the y-coefficient in the second equation.
Keywords: substitution method, system of equations, elimination method
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