標題:

Maths,答案加步驟?

發問:

1) Find the center and radius of the circle 4x^2+4y^2-7x-8y=2 2a) Find the center and radius of the circle 2x^2+2y^2-16x+12y-48=0 2b) Determine whether the points P(-5,2) lie inside, outside or on the circle in part (a)

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最佳解答:

1) Find the center and radius of the circle 4x^2+4y^2-7x-8y=2 Sol 4x^2+4y^2-7x-8y=2 (4x^2-7x)+(4y^2-8y)=2 (x^2-7x/4)+(y^2-2y)=1/2 (x^2-7x/4+49/64)+(y^2-2y+1)=49/64+1+1/2 (x-7/8)^2+(y-1)^2=145/64 圓心:(7/8,1),半徑=√145/8 2a) Find the center and radius of the circle 2x^2+2y^2-16x+12y-48=0 Sol 2x^2+2y^2-16x+12y-48=0 (x^2-8x)+(y^2+6y)=24 (x^2-8x+16)+(y^2+6y+9)=24+16+9 (x-4)^2+(y+3)^2=7^2 圓心:(4,-3),半徑=7 2b) Determine whether the points P(-5,2) lie inside, outside or on the circle in part (a) d^2=[4-(-5)]^2+(-3-2)^2=81+25=106>49 outside

其他解答:

1. 4x^2+4y^2-7x-8y=2 x^2+y^2-7/4 x-2y-0.5=0 center=(7/8,1) radius=[(7/8)^2 +(1)^2 +0.5]^0.5 radius=(145^0.5)/8 (x-7/8)^2 +(y-1)=145/64 2a) 2x^2+2y^2-16x+12y-48=0 center=(4,-3) radius=7 (x-4)^2 +(y+3)^2=7^2 2b (-5-4)^2 +(2-3)^2 =82>49 outside the circle
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