y-2xy=15 x=-1

Question

  it says to solve the equation for y then find the value of y for the given value of x

Answer 1

y-2xy=15 x=-1

 

To solve the equation for y we can factor a y out of both terms on

the left side;

 

y - 2xy = 15

y(1-2x) = 15

 

Note that if we multiply the y through the parentheses we have the starting equation.

Now divide both sides by (1-2x)

 

y = 15/(1-2x)

 

That is the solution for y from the initial equations

 

To find the value of y when x=-1 plug in -1 in place of x and solve

 

y = 15/(1-2(-1)) = 15/(1+2) = 15/3 = 5

Answer 2

Hi Hannah!

 

Well they basically give you half the battle with the "x=-1"

So you plug that in and you get "y-2(-1)y=15"

This becomes "y+2y=15" since the 2 negatives become +

Now you add "y+2y" to get 3y

The end result is "3y=15"

Which by dividing by 3 to isolate the y gives you 5

 

Hope this helps!

Oscar