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Question Number 217058 by ArshadS last updated on 28/Feb/25

The quadratic equation  has two equal roots:       x^2 +(k−3)x+k=0  (a) Find the value of  k.  (b) For this value of  k, solve the equation for x  (c)If  x is the length of a rectangle and its width is x−2,  find the area   of the rectangle.

Thequadraticequationhastwoequalroots:x2+(k3)x+k=0(a)Findthevalueofk.(b)Forthisvalueofk,solvetheequationforx(c)Ifxisthelengthofarectangleanditswidthisx2,findtheareaoftherectangle.

Answered by Rasheed.Sindhi last updated on 28/Feb/25

(a)  For equal roots discriminant  b^2 −4ac=0  (k−3)^2 −4(1)(k)=0  k^2 −10k+9=0⇒k=1,9  (b)  •k=1:   x^2 +(k−3)x+k=0  ⇒x^2 −2x+1=0⇒x=1  •k=9:    x^2 +6k+9=0⇒x=−3  (c)  •x=1  length of rectangle=x=1  width of rectangle=1−2=−1  Impossible  •x=−3: aea is impssible.  area is impossibe in both cases  (i-e There is no rectangle)

(a)Forequalrootsdiscriminantb24ac=0(k3)24(1)(k)=0k210k+9=0k=1,9(b)k=1:x2+(k3)x+k=0x22x+1=0x=1k=9:x2+6k+9=0x=3(c)x=1lengthofrectangle=x=1widthofrectangle=12=1Impossiblex=3:aeaisimpssible.areaisimpossibeinbothcases(ieThereisnorectangle)

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