2a + b = 3 times TWO is easier
4 a + 2 b = 6
4 a - 5 b = 20
-------------------Subtract
0 a + 7 b = -14
so
b = -2 NOT PLUS 2
then
2 a -2 = 3
2 a = 5
a = 5/2
===========================
HERE is your error:
10 - 5b = 20
Take away 10 from both sides
- 5b = 10 NOTE MINUS SIGN!!!
Divide both sides by 5
b = -2
Solve
2a + b = 3
4a - 5b = 20
My attempt
Multiply the first equation by 5
So,
10a + 5b = 15
4a - 5b = 20
Add them together
14a = 35
Divide both sides by 14
a = 2.5
Substitute (I have done it with the second one)
10 - 5b = 20
Take away 10 from both sides
5b = 10
Divide both sides by 5
b = 2
When I checked if the answers were right by fitting them back into the equation it didn't work
Please help
4 answers
your error is in the 3rd last line
from :
10 - 5b = 20
-5b = 10
b = -2
btw, why didn't you sub back into
2a + b = 3, it would have been easier.
Also , it is not a good idea to sub into an equation that you have altered, try going back into the easiest-looking of the original.
from :
10 - 5b = 20
-5b = 10
b = -2
btw, why didn't you sub back into
2a + b = 3, it would have been easier.
Also , it is not a good idea to sub into an equation that you have altered, try going back into the easiest-looking of the original.
Thanks
Very much appreciated☆
Very much appreciated☆
its b =4