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can anyone help with solving the following linear equation?
t=240/r
r=t+22
3 Answers
- MsMathLv 71 decade agoFavorite 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!
- 1 decade ago
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