Question

substitute y= -5/7 into 2x+ 5y =21​

Answer 1

Answer:

Using this method, the two equations are reduced to a single variable equation by eliminating one of the variables.

Step 1: Here, let us eliminate the y term and in order to eliminate the y term, multiply the first equation with the coefficient of y in the second equation and multiply the second equation with the coefficient of y in the first equation so that the coefficients of y terms in both the equations becomes equal.

(3x+5y=21)3⇒9x+15y=63--- (3)

(2x+3y=13)5⇒10x+15y=65 --- (4)

Step 2 : Subtract equation (3) from equation (4)

(10x+15y)−(9x+15y)=65−63⇒x=2.

Step 3: Substitute the values of x in equation (1) or equation (2) to find the value of y.

Here substituting the value of x in the first equation we have,

3(2)+5y=21

5y=21−6

5y=15⇒y=3

∴ The solution of the given pair of equations is x=2,y=3.