Question

Use the matrix method to solve:

x + 4y = 8
2x + y = 9

x=4
y=?

Answer 1

@mathmate

Answer 2

@mathmale

Answer 3

You can solve it by Gaussian elimination, or by Cramer's method.
Which one have you done at school?

Answer 4

none

Answer 5

x is 4 idk y

Answer 6

Well, since you already know x, you don't have to use matrix method to solve for y.
Put x=4 in one of the two equations to reduce the number of unknowns to one, solve for y.

Answer 7

i really dont know how to this the last question

Answer 8

Given x+4y=8
and you know x=4, so put x=4 in the above equation to get
4+4y=8
and try to solve for y.

Answer 9

ok so 4 cancels

Answer 10

Not really, unless you mean you would subtract 4 from both sides.

Answer 11

yeah from both sides

Answer 12

So what do you get for y?

Answer 13

8

Answer 14

Starting with
4+4y=8
Subtract 4 from each side:
4-4 +4y = 8-4
4y = 4
Can you now solve for y?