Question 764794
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 = {{{sqrt(44/5)}}}
y = {{{2*sqrt(11/5)}}}
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 = {{{sqrt(81/5)}}}
x = {{{9*sqrt(1/5)}}}
x ~ 4.025
:
:
Check this on a calc: enter (81/5) + (44/5) results: 25