SOLUTION: Given the linear system X + 2y = 1O 3x + (6 + t)y = 30, (a) Determine a particular value oft so that the system has infinitely many solutions. (b) Determine a particular value

Algebra ->  Matrices-and-determiminant -> SOLUTION: Given the linear system X + 2y = 1O 3x + (6 + t)y = 30, (a) Determine a particular value oft so that the system has infinitely many solutions. (b) Determine a particular value      Log On


   



Question 1175505: Given the linear system
X + 2y = 1O
3x + (6 + t)y = 30,
(a) Determine a particular value oft so that the system
has infinitely many solutions.
(b) Determine a particular value oft so that the system
has a unique solution.
(c) How many different values of t can be selected in
part (b)?

Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
Given the linear system
x+%2B+2y+=+10
3x+%2B+%286+%2B+t%29y+=+30
-----------------------------
(a) Determine a particular value of t so that the system
has infinitely many solutions.
Lines that lay right on top of each other; the linear system has infinitely many solutions, basically it's same line
first equation have x and second equation have 3x, first equation have constant term 10 and second equation have 30=> so, multiplied by 3
then must be 2%2A3=6%2Bt->6=6%2Bt->t=0
x+%2B+2y+=+10..........t=0
3x+%2B+%286+%2B+0%29y+=+30
-----------------------------
x+%2B+2y+=+10
3x+%2B+6y+=+30
------------------------=>the linear system has infinitely many solutions
+graph%28+600%2C600%2C+-10%2C+10%2C+-10%2C+10%2C+-x%2F2%2B5%2C+-3x%2F6%2B30%2F6%29+

(b) Determine a particular value oft so that the system
has a unique solution.
t could any number except 0
x+%2B+2y+=+10..........let's take t=2
3x+%2B+%286+%2B2%29y+=+30
-----------------------------
x+%2B+2y+=+10+
3x+%2B+8y+=+30
-----------------------------

+graph%28+600%2C600%2C+-10%2C+20%2C+-10%2C+20%2C+-x%2F2%2B5%2C+-3x%2F8%2B30%2F8%29+

(c) How many different values of t can be selected in
part (b)?

infinitely number of different values of t+can be selected

Answer by ikleyn(52800) About Me  (Show Source):
You can put this solution on YOUR website!
.

The extended matrix of the system is


    %28matrix%282%2C3%2C+1%2C+2%2C+10%2C++3%2C+6%2Bt%2C+30%29%29.



(a)  the system has infinitely many solutions, if and only if both lines of the coefficient matrix are proportional.


     From the form of the matrix, it is clear that the only value of "t" for it is  t= 0.



(b)  For all other values of "t" the lines of the matrix are not proportional

     Hence, for all values of "t" different from t= 0, the system has a unique solution.



(c)  In part (b),  there are infinitely many possible values of "t".

Solved.

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See the lesson
    - Geometric interpretation of the linear system of two equations in two unknowns
in this site.