a) Use synthetic division to show that 2 is a solution of 2h3 +14h2 − 72 = 0 .
b) Using part a, find the dimensions of a box that has a volume of 72 cubic
inches where the width is twice the height and the length is 7 inches more than the height.

4. Find k so that 4x-3 is a factor of 20x3+23x2-10x+k

Respuesta :

Answer:

Length=9 inches,width=4 inches, height =2 inches.

k= [tex]-\frac{111}{8}[/tex]

Step-by-step explanation:

a) If by synethetic division method the remainder equals i.e in the last row and last column if figure yield is 0 then 2 is one of the factor i.e one of the solution of given equation.

Remainder is 0.

Hence 2 is the solution of given equation.

b) Given a box having volume 72 cubic inches

   Let Height = x inches

   ∵ length is 7 inches more than the height

  ⇒     Length = x+7 inches

  & also width is twice the height

 ⇒      Width = [tex]2\times x[/tex]

   Given   Volume = 72 cubic inches

   [tex]length\times width\times height[/tex] = 72

   [tex](x+7)\times (2x)\times x[/tex] - 72 = 0

From part a, 2 is the solution of above equation

⇒       Length = x+7 = 2+7 = 9 inches

          Width = [tex]2\times2[/tex] = 4 inches

         Height = x = 2 inches

Given [tex]4x-3[/tex] is a factor of [tex]20x^3+23x^{2} -10x+k[/tex]

Hence, [tex]20(\frac{3}{4})^3 +23(\frac{3}{4}) ^{2} -10(\frac{3}{4})+k=0[/tex]

            [tex]\frac{135}{16}+\frac{207}{16}-\frac{120}{16} +k=0[/tex]

                   [tex]\frac{111}{8}+k=0[/tex]

                      k= [tex]-\frac{111}{8}[/tex]


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