Question

Can someone please help me with #7. Substitution method

Answer 1

7. 4x-4y=8...(1) and -x+y=-2,,,(2)

Choose one equation from the two above to derive the third equation from.

I choose -x+y=-2 and i will derive the third equation form it

I will make y the subject of the equation y=-2+x......(3)

Substitute the third equation from the first equation YOU DID NOT USE TO DERIVE THE THIRD EQUATION

`4x-4(-2+x)=8\\4x+8-4x=8\\4x-4x=8-8\\0=0`

As far as I went there are No Solutions for the system of equations for question 7

8.

6x-3y=-9 ....(1)

and

x+y=9....(2)

x=9-y....(3)

`6(9-y)-3y=-9\\54-6y-3y=-9\\-9y=-9-54\\-9y=-63\\(-9y)/(9) =(-63)/(9) \\y=-7`

`x=9-(-7)\\x=9+7\\x=16`