Solve each of the following systems by substitution. 5x-6y-21; x-2y=5?

Question

Solve each of the following systems by substitution. 5x-6y-21; x-2y=5

5x-6y=21
x-2y=5

Answer 1

Isolate "x" or "y" in either equation. Let's isolate "x" in the 2nd equation.

First: add "2y" with both sides (when you move a term to the opposite side, always use the opposite sign).

x - 2y + 2y = 5+2y
x = 5+2y

Sec: substitute "5+2y" with "x" in the 1st equation.

5x - 6y = 21
5(5+2y) - 6y = 21
5(5)+5(2y) - 6y = 21
25+10y - 6y = 21
25+4y = 21 (subtract 25 from both sides).
25-25+4y = 21-25
4y = 21-25
4y = - 4 (divide both sides by 4).
4y/4 = - 4/4
y = - 4/4
y = -1

Third: substitute -1 with "y" in the 2nd equation.

x - 2y = 5
x - 2(-1) = 5
x + 2 = 5 (subtract 2 from both sides).
x + 2 - 2 = 5 - 2
x = 5 - 2
x = 3

Solution Set: (3, -1)

Answer 2

in the past I supply the answer, you should understand the rhyme and reason of the substitution technique. you're on condition that y=2x+3 on your 2nd equation, plug in(replace) what you're given like so: 5x -2(2x+3) = -5 5x - 4x -6= -5 x=a million Now circulate returned on your first equation and resolve for y: y=2x +3 y=2(a million) +3 y = 5 answer: (a million,5)

Answer 3

reread the problem. i think you copied the first part incorrectly. it has to be an equation with an equal sign in order to solve by substitution.
Maybe it should read 5x-6y=21.

Answer 4

5x-6y-21;x-2y=5

5x-6y=21
(x-2y=5)-5

5x-6y=21
-5x+10y= -25
------------------
4y=-4 Therefore y= -1

5x+6=21
5x=15
x=3


x=3, y= _1

Answer 5

5x-6y=21
x-2y=5
x=2y+5

5(2y+5)-6y=21
10y+25-6y=21
4y+25-25=21-25
4y=-4
y=-1

x-2(-1)=5
x+2=5
x+2-2=5-2
x=3

Answer 6

Please make a new question because the first equation does not make sense due to it lacking an equals sign which confuses me.

Once you post the new question, ill be glad to help out