SAT Math › Systems of Equations
The sum of four consecutive even integers is , but their product is
. What is the least of those integers?
Any time the product of consecutive numbers is ,
must be a one of those consecutive numbers, because if it is not, the product will be non-zero. This leaves us with four possibilities, depending on where
is placed in the sequence.
As we can see, ,
,
and
are our numbers in question, meaning
is our answer as the lowest number.
Note that it is possible to use algebra and set up a system of equations, but it's more time-consuming, which could hinder more than help in a standardized test setting.
If 7_x_ + y = 25 and 6_x_ + y = 23, what is the value of x?
2
6
7
11
20
You can subtract the second equation from the first equation to eliminate y:
7_x_ + y = 25 – 6_x_ + y = 23: 7_x_ – 6_x_ = x; y – y = 0; 25 – 23 = 2
x = 2
You could also solve one equation for y and substitute that value in for y in the other equation:
6_x_ + y = 23 → y = 23 – 6_x_.
7_x_ + y = 25 → 7_x_ + (23 – 6_x_) = 25 → x + 23 = 25 → x = 2
The sum of four consecutive even integers is , but their product is
. What is the least of those integers?
Any time the product of consecutive numbers is ,
must be a one of those consecutive numbers, because if it is not, the product will be non-zero. This leaves us with four possibilities, depending on where
is placed in the sequence.
As we can see, ,
,
and
are our numbers in question, meaning
is our answer as the lowest number.
Note that it is possible to use algebra and set up a system of equations, but it's more time-consuming, which could hinder more than help in a standardized test setting.
If 7_x_ + y = 25 and 6_x_ + y = 23, what is the value of x?
2
6
7
11
20
You can subtract the second equation from the first equation to eliminate y:
7_x_ + y = 25 – 6_x_ + y = 23: 7_x_ – 6_x_ = x; y – y = 0; 25 – 23 = 2
x = 2
You could also solve one equation for y and substitute that value in for y in the other equation:
6_x_ + y = 23 → y = 23 – 6_x_.
7_x_ + y = 25 → 7_x_ + (23 – 6_x_) = 25 → x + 23 = 25 → x = 2
How many solutions are there to the following system of equations?
There are an infinite number of solutions.
There is 1 single solution.
There are 2 solutions.
There are 3 solutions.
There are no solutions.
If we use elimination to solve this system of equations, we can add the two equations together. This results in 0=0.
When elimination results in 0=0, that means that the two equations represent the same line. Therefore, there are an infinite number of solutions.
How many solutions are there to the following system of equations?
There are an infinite number of solutions.
There is 1 single solution.
There are 2 solutions.
There are 3 solutions.
There are no solutions.
If we use elimination to solve this system of equations, we can add the two equations together. This results in 0=0.
When elimination results in 0=0, that means that the two equations represent the same line. Therefore, there are an infinite number of solutions.
At what point will the lines and
intersect?
(1, 6)
(1, –6)
(6, 1)
(–1, 6)
(6, –1)
In order to find this point, we must find the solution to the system of equations. we will use substitution, setting the two expressions for y equal to one another.
Then we plug this value back into either expression for y, giving us
So the point is (1, 6).
At what point will the lines and
intersect?
(1, 6)
(1, –6)
(6, 1)
(–1, 6)
(6, –1)
In order to find this point, we must find the solution to the system of equations. we will use substitution, setting the two expressions for y equal to one another.
Then we plug this value back into either expression for y, giving us
So the point is (1, 6).
What is the value of in the following system of equations? Round your answer to the hundredths place.
You can solve this problem in a number of ways, but one way to solve it is by using substitution. You can begin to do that by solving for in the first equation:
Now, you can substitute in that value of into the second equation and solve for
:
Let's consider this equation as adding a negative 3 rather than subtracting a 3 to make distributing easier:
Distribute the negative 3:
We can now combine like variables and solve for :
What is the value of in the following system of equations? Round your answer to the hundredths place.
You can solve this problem in a number of ways, but one way to solve it is by using substitution. You can begin to do that by solving for in the first equation:
Now, you can substitute in that value of into the second equation and solve for
:
Let's consider this equation as adding a negative 3 rather than subtracting a 3 to make distributing easier:
Distribute the negative 3:
We can now combine like variables and solve for :