Leavitt957 Leavitt957
  • 12-04-2015
  • Mathematics
Answered


1-29
In the equation x² + kx + 54=0, one root is twice the other root. The value(s) of k is (are)
A. -5.2
B. 15.6
C. 22.0
D. ± 5.2
E. ± 15.6

Answer :

konrad509
konrad509 konrad509
  • 12-04-2015
[tex]x_1+x_2=-\dfrac{b}{a}=-k\\ x_1x_2=\dfrac{c}{a}=54\\ x_1=2x_2\\\\ 2x_2+x_2=-k\\ 3x_2=-k\\ x_2=-\dfrac{k}{3}\\\\ 2x_2\cdot x_2=54\\ 2x_2^2=54\\ x_2^2=27\\\\ \left(-\dfrac{k}{3}\right)^2=27\\ \dfrac{k^2}{9}=27\\ k^2=243\\ k=\pm\sqrt{243}\\ k\approx\pm15.6 [/tex]
Answer Link

Other Questions

whick is larger 3kL or 30000 L
write 172 as a fraction simplest form
Write an equation to express the value of h k
find the slope of a line perpendicular to the line whose equation is 3y 2x 6
Which of the following is not a function or purpose of the cell membrane Select one a Keep toxins out of a cell b Provide physical support and protection for th
Which quantity can be calculated for a solid compound given only the formula of the compound and the Periodic Table of the Elements 1 the density of the compoun
Which expression is equivalent to the given expression 1319 x
I Need Help With 8 9 10
Red blood cells that are bathed in blood neither shrink nor swell and burst If the concentration of blood is 05 M what could be the concentration of cytoplasm o
The sum of three integers is 92 The second number is three times the first number The third number is ten less than twice the first number Find the integers I h