SOLUTION: is it the right way to square root the whole equation for example: x^2 + y^2 = 16 because i have to find the point of interse2ction of that equation and 2y + x = 3 what i did w

Question 702419: is it the right way to square root the whole equation
for example: x^2 + y^2 = 16
because i have to find the point of interse2ction of that equation and 2y + x = 3
what i did was i put square root on the first equation and then solve it by simultaneous equation however i have got the wrong answer.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
is it the right way to square root the whole equation
for example: x^2 + y^2 = 16
find the point of interse2ction of that equation and 2y + x = 3
-----------------
2y + x = 3
x = -2y + 3
Sub for x in the other eqn
(-2y + 3)^2 + y^2 = 16
4y^2 - 12y + 9 + y^2 = 16
5y^2 - 12y - 7 = 0

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=284 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 2.88522995463527, -0.485229954635272. Here's your graph:

-----------
y = 6/5 + sqrt(71)/5
x = -2y + 3
x = -12/5 - 2sqrt(71)/5 + 3
--> point (3/5 - 2sqrt(71)/5,6/5 + sqrt(71)/5)
========================
y = 6/5 - sqrt(71)/5
x = -2y + 3
x = -12/5 + 2sqrt(71)/5 + 3
--> point (3/5 + 2sqrt(71)/5,6/5 - 2sqrt(71)/5)

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