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Please help me! : Given the equation (x-3)^2+(y+1)^2=9, determine which of the following statements are true. Check all that apply.

A. The equation represents a circle with a radius of length 9 units.
B. The equation represents a circle that is centered at (3,-1)
C. The equation represents a circle that is centered at (-3,1)
D. The equation represents a circle that intersects the x-axis twice.
E. The equation represents a circle that does not intersect the y-axis.


Sagot :

Answer:

The correct statements are B and D.

Step-by-step explanation:

The equation [tex](x-3)^2+(y+1)^2=9[/tex] reminds us of the circle equation [tex]\boxed{(x-a)^2+(y-b)^2=r^2}[/tex], where:

  • [tex](a,b)[/tex] = coordinate of the circle's center
  • [tex]r[/tex] = radius

In order to find the center and the radius, we convert the equation into the standard form:

[tex](x-3)^2+(y+1)^2=9[/tex]

[tex](x-(3))^2+(y-(-1))^2=3^2[/tex]

Therefore:

  • center [tex](a,b)[/tex] = (3, -1)
  • radius ([tex]r[/tex]) = 3

Hence, options A and C are incorrect and option B is correct.

for option D:

When the equation intersects the x-axis, the y-value = 0.

[tex](x-3)^2+(y+1)^2=9[/tex]  →  substitute [tex]y[/tex] with 0

[tex](x-3)^2+(0+1)^2=9[/tex]

[tex](x-3)^2=9-1[/tex]

[tex]x-3=\pm\sqrt{8}[/tex]

[tex]x=\pm2\sqrt{2} +3[/tex]

[tex]x=2\sqrt{2} +3\ or\ -2\sqrt{2} +3[/tex]

Since there are 2 solutions for x-value, then the equations intersects the x-axis twice. (option D is correct)

for option E:

When the equation intersects the y-axis, the x-value = 0.

[tex](x-3)^2+(y+1)^2=9[/tex]  →  substitute [tex]x[/tex] with 0

[tex](0-3)^2+(y+1)^2=9[/tex]

[tex](y+1)^2=9-9[/tex]

[tex]y+1=0[/tex]

[tex]y=-1[/tex]

Since there is only 1 solution for y-value, then the equations tangent to the y-axis. (option E is incorrect)