Help Me please.
Solve for all values of x and y
\(\left \{x^2-3y^2=13 \right \} \left \{x-2y=1 \right \}\)
x - 2y = 1
Add 2y to both sides of the equation.
x = 1 + 2y
x2 - 3y2 = 13
Since x = 1 + 2y we can replace x with 1 + 2y .
(1 + 2y)2 - 3y2 = 13
Multiply out (1 + 2y)2 .
(1 + 2y)(1 + 2y) - 3y2 = 13
(1)(1) + (1)(2y) + (2y)(1) + (2y)(2y) - 3y2 = 13
1 + 2y + 2y + 4y2 - 3y2 = 13
1 + 4y + y2 = 13
y2 + 4y + 1 = 13
Subtract 13 from both sides.
y2 + 4y - 12 = 0
Factor the left side.
(y + 6)(y - 2) = 0
Set each factor equal to zero and solve for y .
y + 6 = 0 or y - 2 = 0
y = -6 or y = 2
Now let's use the equation x = 1 + 2y to find x .
If y = -6 then x = 1 + 2(-6) = 1 + -12 = -11
So one solution is x = -11 and y = -6 .
If y = 2 then x = 1 + 2(2) = 1 + 4 = 5
So another solution is x = 5 and y = 2 .
The solution set is { (-11, -6), (5, 2) }
x^2 - 3y^2 = 13
x - 2y = 1
Rearrange the second equation as
x = 2y + 1
Sub this into the first equation for x
(2y + 1)^2 - 3y^2 = 13 simplify
4y^2 + 4y + 1 - 3y^2 = 13
y^2 + 4y + 1 = 13 subtract 1 from both sides
y^2 + 4y - 12 = 0 factor
(y + 6) (y - 2) = 0
Setting each factor to 0 and solving for y we have
y + 6 = 0 y - 2 = 0
y = -6 y = 2
And when y = -6 .... x = 2(-6) + 1 = -11
And when y = 2..... x = 2(2) + 1 = 5
So....the solutions are
(x,y) = ( 5, 2) and ( -11, -6)