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MAT3700
EXAM PACK
DISTINCTION QUALITY
UNISA EXAM
, MAT3700 2025
Solve the following first-order differential equations:
QUESTION 1: x y 3 dy 4ydx (4)
ANSWER: x y 3 dy 4ydx
y 3 4
dy dx
y x
3 4
1 y dy x dx
y 3 ln y 4 ln x C
QUESTION 2: x 3 y 3 dx 3 xy 2dy 0 [Hint: Put y vx ] (7)
ANSWER:
x 3
y 3 dx 3 xy 2dy 0
dy dv
Put y = vx then v x
dx dx
x 3
v 3 x 3 dx 3 x 3v 2dy 0
dy x3 v 3x3
dx 3 x 3v 2
dv 1 v 3
vx
dx 3v 2
2
3v
dx
dv
1 2v 3 x
1
ln 1 2v 3 ln x C
2
3
1 y
ln 1 2 ln x C
2 x
-1-
Open Rubric
MAT3700
EXAM PACK
DISTINCTION QUALITY
UNISA EXAM
, MAT3700 2025
Solve the following first-order differential equations:
QUESTION 1: x y 3 dy 4ydx (4)
ANSWER: x y 3 dy 4ydx
y 3 4
dy dx
y x
3 4
1 y dy x dx
y 3 ln y 4 ln x C
QUESTION 2: x 3 y 3 dx 3 xy 2dy 0 [Hint: Put y vx ] (7)
ANSWER:
x 3
y 3 dx 3 xy 2dy 0
dy dv
Put y = vx then v x
dx dx
x 3
v 3 x 3 dx 3 x 3v 2dy 0
dy x3 v 3x3
dx 3 x 3v 2
dv 1 v 3
vx
dx 3v 2
2
3v
dx
dv
1 2v 3 x
1
ln 1 2v 3 ln x C
2
3
1 y
ln 1 2 ln x C
2 x
-1-
Open Rubric