Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

can anyone help with solving the following linear equation?

t=240/r

r=t+22

3 Answers

Relevance
  • MsMath
    Lv 7
    1 decade ago
    Favorite Answer

    t = 240/r

    r = t + 22

    Replace t with 240/r in the second equation

    r = 240/r + 22

    Multiply both sides by r

    r^2 = 240 + 22r

    Subtract 22r from each side, and subtract 240 from each side

    r^2 - 22r - 240 = 0

    Factor

    (r-30)(r+8) = 0

    Set each factor equal to zero

    r-30 = 0 or r+8 = 0

    r = 30 or r = -8

    Now find the corresponding t value.

    t = 240/r

    So t = 240/30 = 8 or t = 240/-8 = -30

    Answer: r = 30, t = 8,

    or r = -8, t = -30

  • 1 decade ago

    Substitute one equation into the other.

    1. t=240/r

    2. r=t+22

    Rearrange equation 2 to give

    t= r-22 and substitute into 1.

    r-22=240/r

    Multiply by r each side

    r^2 - 22r = 240

    or

    r^2 -22r -240 = 0

    Using r = (-b +/- sqrt (b^2-4ac) )/ 2a

    r= ( 22 +/- sqrt(22^2 -4*1*(-240) )/ 2(1)

    r= (22 +/- sqrt (484+960))/2

    = (22+/- sqrt(1444))/2 = (22 +/- 38)/2

    so r = (22+38)/2 = 30 or r= (22-38)/2 = -8

    so for r = 30, t= 8 and for r= -8, t = -30

    Two solutions

    Verify in each equation to ensure that this is correct!

  • You can solve it by graphing the two lines and detect the point of intersection

    or by algebra

    t = 240/r equ. 1

    r = t+22 equ. 2

    by substitute from equ. 1 in equ. 2

    r =(240/r) + 22

    multiply all the equ. By (r)

    r^2 - 22r - 240 = 0

    factors

    (r+8)(r-30) = 0

    then we have

    r=-80 OR r=30

    i hope you get it

    this is my best to explain

    thanx bye

Still have questions? Get your answers by asking now.