How do you solve the system 4x^2-56x+9y^2+160=04x256x+9y2+160=0 and 4x^2+y^2-64=04x2+y264=0?

2 Answers
Jul 9, 2016

y^2 = 64 - 4x^2y2=644x2

y =+- sqrt(64 - 4x^2)y=±644x2

4x^2 - 56x + 9(sqrt(64 - 4x^2))^2 + 160 = 04x256x+9(644x2)2+160=0

4x^2 - 56x + 9(64 - 4x^2) + 160 = 04x256x+9(644x2)+160=0

4x^2 - 56x + 576 - 36x^2 + 160 = 04x256x+57636x2+160=0

0 = 32x^2 + 56x - 7360=32x2+56x736

0 = 8(4x^2 + 7x - 92)0=8(4x2+7x92)

0 = 8(4x^2 - 16x + 23x - 92)0=8(4x216x+23x92)

0 = 8(4x(x - 4) + 23(x - 4))0=8(4x(x4)+23(x4))

0 = 8(4x + 23)(x - 4)0=8(4x+23)(x4)

x = -23/4 and 4x=234and4

Case 1:

4(-23/4)^2 + y^2 - 64 = 04(234)2+y264=0

4(529/16) + y^2 - 64 = 04(52916)+y264=0

y^2 = 64 - 529/4y2=645294

y = O/y=

Case 2:

4(4)^2+ y^2 - 64 = 04(4)2+y264=0

4(16) + y^2 - 64 = 04(16)+y264=0

y^2 = 64 - 64y2=6464

y^2 = 0y2=0

y = 0y=0

The only real solution is x = 4x=4, y = 0y=0.

Thus, the solution set is {-4, 0}{4,0}.

Hopefully this helps!

Jul 9, 2016

y = 0y=0 and x = 4x=4

Explanation:

Making x_2=x^2,y_2=y^2x2=x2,y2=y2 and solving for x_2,y_2x2,y2 the system

{ (4 x_2+9y_2=56x-160), (4x_2+y_2=64) :}

we obtain

{ (x_2 = 1/4 (92 - 7 x)), (y_2 = 7 x-28) :}

Now we solve

x^2 = 1/4 (92 - 7 x)

obtaining x = {-23/4,4}

and

y = pm sqrt(7x-28)

or

y = pm sqrt(7 cdot 4-28) = 0 excluding complex solutions.

we have

y = 0 and x = 4

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