I have a series of 3 questions.
Mathematics
littlelove6711
Question
I have a series of 3 questions.
1 Answer

1. User Answers liemonder
1)
I:d+e=2
II:de=4
Isolate d in I:
d=2e
substitute into II:
II:2ee=4
2e=2
e=1
substitute e into II:
d(1)=4
d+1=4
d=3
the solution is (3,1)
2)
I:y3x=7
II:21+9x=3y
Isolate y in I:
y=7+3x
substitute y into II:
21+9x=3*(7+3x)
21+9x=21+9x
x=x
> Infinite amount of solutions
note: I*3=II:
3y9x=21
3y=21+9x
so you have two identical lines
3)
I:5x+2y=7
II:y=x7
Substitute y into I:
5x+2*(x7)=7
5x+2x14=7
7x=7
x=1
Substitute x into II:
y=(1)7
y=8
so the solution is (1,8)