SOLUTION: I multiplied the bottom equation by -4 to cancel out the y's then subtracted the two equations but got the wrong answer.
Solve each system of equations.
9x^2+4y^2=144
x^2+
Algebra.Com
Question 764794: I multiplied the bottom equation by -4 to cancel out the y's then subtracted the two equations but got the wrong answer.
Solve each system of equations.
9x^2+4y^2=144
x^2+y^2=25
Found 2 solutions by ankor@dixie-net.com, DrBeeee:
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Solve each system of equations.
9x^2 + 4y^2 = 144
x^2 + y^2 = 25
:
After you multiply the 2nd equation by -4, you want add the equations
9x^2 + 4y^2 = 144
-4x^2 -4y^2 = -100
---------------------
5y^2 = 44
y^2 = 44/5
y =
y =
y ~ 2.966
:
Find x using the 2n original equation; y^2 = 44/5
x^2 + 44/5 = 25
multiply both sides by 5
5x^2 + 44 = 125
5x^2 = 125 - 44
5x^2 = 81
x^2 = 81/5
x =
x =
x ~ 4.025
:
:
Check this on a calc: enter (81/5) + (44/5) results: 25
Answer by DrBeeee(684) (Show Source): You can put this solution on YOUR website!
After you multiplied by -4, you should ADD the two equations.
(1)
(2) times -4 becomes
(3)
If you subtract (3) from (1) you get a +8y^2 term, which you don't want. If you add (3) and (1) you get
(4) or
(5) or
(6) or approx. 3
Put (5) into (2) and get
(7) or
(8) or
(9) or 16.2
(10) or approx. 4
Note that we get four solutions (intersecting points)
(16) (x,y) = {(+sqrt(8.8),+sqrt(16.2)),(+sqrt(8.8),-sqrt(16.2)),(-sqrt(8.8),+sqrt(16.2)),(-sqrt(8.8),-sqrt(16.2))}
These four point result from the ellipse (I think) of (1) and the circle (I know) of (2)
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