Question and Answers Forum

All Questions      Topic List

Algebra Questions

Previous in All Question      Next in All Question      

Previous in Algebra      Next in Algebra      

Question Number 102078 by Jamshidbek2311 last updated on 06/Jul/20

Answered by mr W last updated on 06/Jul/20

METHOD I  x^2 +y^2  is the square of the distance  from point (x,y) to the origin (0,0).    (x+5)^2 +(y−12)^2 =14^2  is the circle  with radius 14 and center at (−5,12).  distance from (−5,12) to the origin  is (√((−5)^2 +12^2 ))=13, the minimum  distance from a point on the circle to  the origin is then 14−13=1 and the   maximum distance is 14+13=27.  ⇒(x^2 +y^2 )_(min) =1^2 =1  ⇒(x^2 +y^2 )_(max) =27^2 =729

METHODIx2+y2isthesquareofthedistancefrompoint(x,y)totheorigin(0,0).(x+5)2+(y12)2=142isthecirclewithradius14andcenterat(5,12).distancefrom(5,12)totheoriginis(5)2+122=13,theminimumdistancefromapointonthecircletotheoriginisthen1413=1andthemaximumdistanceis14+13=27.(x2+y2)min=12=1(x2+y2)max=272=729

Answered by mr W last updated on 06/Jul/20

METHOD II  k=x^2 +y^2   F=x^2 +y^2 +λ[(x+5)^2 +(y−12)^2 −14^2 ]  (∂F/∂x)=2x+2λ(x+5)=0 ⇒x=−((5λ)/(λ+1))  (∂F/∂y)=2y+2λ(y−12)=0 ⇒y=((12λ)/(λ+1))  (−((5λ)/(λ+1))+5)^2 +(((12λ)/(λ+1))−12)^2 −14^2 =0  5^2 (1−(λ/(λ+1)))^2 +12^2 (1−(λ/(λ+1)))^2 −14^2 =0  13^2 (1−(λ/(λ+1)))^2 =14^2   ⇒1−(λ/(λ+1))=±((14)/(13))  ⇒λ+1=±((13)/(14))  ⇒λ=−(1/(14)) or −((27)/(14))  with λ=−(1/(14)):  x=−5×((−(1/(14)))/(1−(1/(14))))=(5/(13))  y=12×((−(1/(14)))/(1−(1/(14))))=−((12)/(13))  ⇒k=x^2 +y^2 =((5/(13)))^2 +(−((12)/(13)))^2 =1=min.  with λ=−((27)/(14)):  x=−5×((−((27)/(14)))/(1−((27)/(14))))=−5×((27)/(13))  y=12×((−((27)/(14)))/(1−((27)/(14))))=12×((27)/(13))  ⇒k=x^2 +y^2 =(−5×((27)/(13)))^2 +(12×((27)/(13)))^2 =729=max.

METHODIIk=x2+y2F=x2+y2+λ[(x+5)2+(y12)2142]Fx=2x+2λ(x+5)=0x=5λλ+1Fy=2y+2λ(y12)=0y=12λλ+1(5λλ+1+5)2+(12λλ+112)2142=052(1λλ+1)2+122(1λλ+1)2142=0132(1λλ+1)2=1421λλ+1=±1413λ+1=±1314λ=114or2714withλ=114:x=5×1141114=513y=12×1141114=1213k=x2+y2=(513)2+(1213)2=1=min.withλ=2714:x=5×271412714=5×2713y=12×271412714=12×2713k=x2+y2=(5×2713)2+(12×2713)2=729=max.

Answered by mr W last updated on 06/Jul/20

METHOD III  k=x^2 +y^2 =d^2   let x=d cos θ, y=d sin θ  (d cos θ+5)^2 +(d sin θ−12)^2 =14^2   d^2 +2d(5 cos θ−12 sin θ)−27=0  d^2 +26d(sin α cos θ−cos α sin θ)−27=0  d^2 +26d sin (α−θ)−27=0  d=−13 sin (α−θ)+(√(169 sin^2  (α−θ)+27))  d_(max) =13+(√(169+27))=13+14=27  d_(min) =−13+(√(169+27))=−13+14=1  k=x^2 +y^2 =d^2 =27^2 =729=max.  k=x^2 +y^2 =d^2 =1^2 =1=min.

METHODIIIk=x2+y2=d2letx=dcosθ,y=dsinθ(dcosθ+5)2+(dsinθ12)2=142d2+2d(5cosθ12sinθ)27=0d2+26d(sinαcosθcosαsinθ)27=0d2+26dsin(αθ)27=0d=13sin(αθ)+169sin2(αθ)+27dmax=13+169+27=13+14=27dmin=13+169+27=13+14=1k=x2+y2=d2=272=729=max.k=x2+y2=d2=12=1=min.

Answered by mr W last updated on 06/Jul/20

METHOD IV  x=−5+14 cos θ  y=12+14 sin θ  x^2 +y^2 =5^2 +12^2 +14^2 +28(−5 cos θ+12 sin θ)  =365+28×13(−sin α cos θ+cos α sin θ)  =365+28×13 sin (θ−α)  max. =365+28×13=729  min. =365−28×13=1

METHODIVx=5+14cosθy=12+14sinθx2+y2=52+122+142+28(5cosθ+12sinθ)=365+28×13(sinαcosθ+cosαsinθ)=365+28×13sin(θα)max.=365+28×13=729min.=36528×13=1

Answered by john santu last updated on 07/Jul/20

method JS  x^2 +y_(min) ^2  = [ r −(√(x_c ^2 +y_c ^2 )) ]^2   x^2 +y_(max) ^2  = [ r +(√(x_c ^2 +y_c ^2 )) ]^2

methodJSx2+ymin2=[rxc2+yc2]2x2+ymax2=[r+xc2+yc2]2

Terms of Service

Privacy Policy

Contact: info@tinkutara.com