Solve algebraically plzz help

Question

y=2x+5 and y=-4x+7

Answer 1

y = 2x + 5

y = -4x + 7

 

2x + 5 = -4x + 7      Transitive property of equality

6x + 5 = 7                Add 4x to both sides

6x = 2                      Subtract 5 from both sides

x = 1/3                     Divide both sides by 6

 

Substitute 1/3 for x in either equation to determine the value of y.

Answer 2

if y=2x+5 then we know:

 

y-5=2x so x=(y-5)/2

 

if y=4x+7 then we know

 

y=4*((y-5)/2)+7 so y=4*y/2-4*5/2+7 or y=2*y-10+7 or y=2y-3 so y-2y=-3 or -y=-3.

 

This leads us to conclude that y=3 and if y=3 then x=(3-5)/2=-2/2=-1.

 

So y=3 and x=-1

Answer 3

Hi Ed.

 

Since both of these = y, then they = each other, so...

 

2x+5=-4x+7

 

Add 4x to both sides

 

6x+5=7

 

Subtract 5 from both sides

 

6x=2

 

Divide both sides by 6

 

x=2/6

 

Reduce the fraction

 

x=1/3