Question

Solve the following system by substitution.
X+2y=14
6x+3y=21

Answer 1

Step-by-step explanation:

x + 2y = 14 ...............(1)

6x + 3y = 21 ..............(2)

Solve for x in equation 1

When x + 2y = 14

Therefore x = 14 - 2y ...................(3)

Now put equation 3 in equation 2 and solve

6x + 3y = 21 .............(2)

6(14 - 2y) + 3y = 21

Open the bracket and resolve

84 - 12y + 3y = 21

-9y + 84 =21

Now collect the like terms

-9y + 84 = 21

-9y = 21 - 84

-9y = -63

Divide through by -9 to get y

y = -63/-9

y = 7

Substitute for y in equation( 3 )to x

x= 14 - 2y............(3)

So, x = 14 - 2(7)

x = 14 - 14

x = 0.

Therefore x = 0 and y = 7

Check: From equation (1)

x + 2y = 14

Now, put x = 0 and y = -2

Therefore, 0 +2(7) =14

0 +14 = 14