Ms. Math Teacher's CyberClassroom: MYP Algebra 2 - Ch10

Friday, October 17, 2008

p. 604 #4

What did the student do wrong? Write the correct equation.

Anonymous said...: bwThe student was wrong when he wrote the equation x^2+y^2=4 because 4 is suppose to be 4^2, which equals 16. The student is wrong because he forgot to square the radius. The correct equation is x^2+y^2=16; 4:15 PM
Anonymous said...: The standard form for the equation of a circle is x^2 + y^2 = r^2, r being the radius. Therefore the equation for a circle with a radius of 4 should be x^2 + y^2 = 16. The student wrote x^2 + y^2 = 4, so they forgot to square the radius.; 4:30 PM
Anonymous said...: To write the equation of a circle you have to square r, the radius, and the student didn't do that. the equation should be x^2+y^2=16 instead of x^2+y^2=4; 6:55 PM
Anonymous said...: the student didnt square the radius. the standard equation of a cirle is x^2 + y^2 = r^2. the term "r" refers to the radius and if the radius is 4, then the sum of x^2 + y^2, should be 16 not 4.; 10:40 PM
Anonymous said...: Error Analysis: x^2 + y^2 = 4, equation of a circle, r = 4

The error here is that the equation of a circle is x^2 + y^2 = r^2. The radius in the proposed equation is 2, but it should be 4, so the error is making x^2 + y^2 equal 4, whereas it should equal 16.; 11:39 PM
Anonymous said...: The student forgot to square the 4 to make it 16. The formula for a circle is x^2+y^2=r^2 therefore if the radius given is 4 , then the correct equation is
x^2+y^2=16; 3:53 PM

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