Simultaneous Equation question: x + 4y = 6, y + 7 = 4x

[Caldari]

Hi there,

I am a little confused about this question. I think i have to transpose but i am really bad and have a mind blank tonight

Here is the question

Find the values of X and Y

x + 4y = 6 and y + 7 = 4x

I am confused because i thought rearranging i could end up with

x + 4y = 6 and y - 4x = -7

but i think this is wrong and i am getting myself muddled up.

Any help would be appreciated thanks again.

 

[stapel]

Find the values of X and Y

x + 4y = 6 and y + 7 = 4x

I'll assume that "X" and "Y" are typoes for "x" and "y", respectively, as otherwise the exercise cannot be completed without further information.

I am confused because i thought rearranging i could end up with

x + 4y = 6 and y - 4x = -7

but i think this is wrong...

It's not "wrong"; it's just unhelpful. It leads to no substitutions; it leads to no cancellations. So let's try any one of many other options. For instance:

. . . . .y + 7 = 4x

Then:

. . . . .y = 4x - 7

Substituting into the first equation, we get:

. . . . .x + 4(4x - 7) = 6

Expanding and simplifying, we get:

. . . . .x + 16x - 28 = 6

. . . . .17x - 28 = 6

. . . . ....

...and so forth. It's not that the above is the "right" way; it's just a maybe more-useful way.

 

[Steven G]

Hi there,

I am a little confused about this question. I think i have to transpose but i am really bad and have a mind blank tonight

Here is the question

Find the values of X and Y

x + 4y = 6 and y + 7 = 4x

I am confused because i thought rearranging i could end up with

x + 4y = 6 and y - 4x = -7

but i think this is wrong and i am getting myself muddled up.

Any help would be appreciated thanks again.

So you are not sure if y + 7 =4x is the same as y - 4x = -7

Just pick values for y and 4x that work. Like 3 + 7 =10 (so 3 is y and 4x is 10). So y -4x -7 becomes 3 - 10 = -7 AND that is correct! So yes, y + 7 =4x can be written as y - 4x = -7.

Now YOU never have to question if you rewrote the equation incorrectly!