Question

s-7t+42=0
s-3t=6
solve the linear equation in two variable by cross multiplication method​

Answer 1

Answer:

Solve the following pair of equations by substitution method:

7x − 15y = 2 (1)

x + 2y = 3 (2)

Solution :

Step 1 : We pick either of the equations and write one variable in terms of the other. Let us consider the Equation (2) :

x + 2y = 3

and write it as x =3 − 2y (3)

Step 2 : Substitute the value of x in Equation (1). We get

7(3 − 2y) − 15y = 2

i.e., 21 − 14y − 15y =2

i.e., −29y = −19

Therefore, y = 19/29

Step 3 : Substituting this value of y in Equation (3), we get

x =3 − 2 (19/29) = 49/29

Therefore, the solution is x = 49/29 , y = 19/29

Verification : Substituting x = 49/29 and y = 19/29 , you can verify that both the Equations (1) and (2) are satisfied.

To understand the substitution method more clearly, let us consider it stepwise:

Step 1 : Find the value of one variable, say y in terms of the other variable, i.e., x from either equation, whichever is convenient.

Step 2 : Substitute this value of y in the other equation, and reduce it to an equation in one variable, i.e., in terms of x, which can be solved. Sometimes, as in Examples 9 and 10 below, you can get statements with no variable. If this statement is true, you can conclude that the pair of linear equations has infinitely many solutions. If the statement is false, then the pair of linear equations is inconsistent.

Step 3 : Substitute the value of x (or y) obtained in Step 2 in the equation used in Step 1 to obtain the value of the other variable.

Remark : We have substituted the value of one variable by expressing it in terms of the other variable to solve the pair of linear equations. That is why the method is known as the substitution method.

HOPE THIS HELP YOU ARMY

SARANGHAE

PURPLE YOU