Question

I need help with Matrices please

Answer 1

Have you started by ruling out the clearly incorrect choices (hint: by setting up the augmented matrix for yourself)?

Answer 2

yes C and D are incorrect are they not

Answer 3

And finally, plug in the solution (you could try solving it, but this is faster). See if it works otherwise pick A.

Answer 4

x = 15 y = 10

Answer 5

plugging in works; but another way is to notice the slopes ...

Answer 6

No solution then?

Answer 7

Do the lines intersect or not?

Answer 8

Or did you try plugging it in?

Answer 9

3(10) = 15 - 9(15)
Does that work? No!

Answer 10

I tried plugging it in

Answer 11

it has no solution . I mean that A. is correct

Answer 12

one way to do this (and get practice setting up an augmented matrix)
is move all the variables to the left hand side, and put in alphabetical order
3y = 15 -9x --> 9x + 3y = 15
-6x = 2y+10 --> -6x + -2y = 10

drop the "letters"
9 3 | 15
-6 -2 | 10

if you get this far , you have only 2 choices: A or B

notice the top line can be simplified. divide all entries by 3:
3 1 | 5
-6 -2 | 10

notice we can divide the bottom line by -2
3 1 | 5
3 1 | -5

the first line says 3x + y =5
and the second line says 3x + y = -5
both cannot be true, so there is no solution

or you could subtract the bottom line from the top line and get

3 1 | 5
0 0 | -10

the last line says 0x + 0y = -10 or 0 = -10
which clearly is not possible. no solution.

Answer 13

Alright I thought so thank you

Answer 14

Fortuitously ,i was correct because i first took its discriminant
which was zero so it has no solution