which of the following are linear equations?
1) 4x+6=8
2) 4x-5y=9
3)
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CBSE
Mathematics
Grade 8
Linear Equations in Two Variables
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How do you solve 4x−3y=8 and 2x+5y=−9?
Answer
This problem deals with solving the system of linear equations in x and y. This is done by adding or subtracting a multiple of one equation to the other equation, in such a way that either the x-terms or the y-terms cancel out. Then solve for x(or y, whichever left) and substitute back to get the other coordinate.
Step-by-step explanation:
Given a pair of linear equations in x and y, which are given by 4x−3y=8 and 2x+5y=−9,
Now we have to solve these two equations in order to get the values of x and y.
Consider the given two equations and rearrange them to solve accordingly.
Consider the first equation, as given below:
⇒4x−3y=8
Now consider the second equation, as given below:
⇒2x+5y=−9
Now multiplying the second equation with 2, so as match the coefficient of xin the first equation, so that we can solve both the equations in a simpler way, as shown below:
⇒2(2x+5y=−9)
⇒4x+10y=−18
Now subtracting the first and second equation, as shown below:
⇒4x−3y=8
⇒4x+10y=−18
⇒−3y−10y=8−(−18)
On simplification of the above two equations, as given below:
⇒−13y=26
∴y=−2
Substituting the value of y=−2, in the first equation 4x−3y=8, as given below:
⇒4x−3y=8
⇒4x−3(−2)=8
Simplifying the above equations, as given below:
⇒4x+6=8
Grouping the constants to the other side of the equation, gives:
⇒4x=8−6
⇒4x=2
Now divide the above equation by 2, as shown:
∴x=12
Hence the values of x=12 and y=−2.
The values of x and y are 12 and -2 respectively.
Answer:
4x+6=8
4x=8-6
4x=2
x=2/4
2nd question I don't no plz mark as Brianlist