1. Direct variation
If one quantity increases (or decreases) in a
ratio, the other quantity increases (or
the same ratio
2. 𝑦 = 𝑘𝑥
Equation form of direct variation
𝑘 is a constant, we say that 𝑦 varies directly as 𝑥.
We also say that 𝑦 is proportional to 𝑥.
𝑘 is called constant of variation
or the constant of proportionality
3. Mr. sacay went to a restaurant and bought some crabs at
P35.00 per 100G.
Weight of
Cooked
Crabs
100 200 300 500 800
Cost of
Cooked
Crabs
35 70 105 175 280
4. The cost of constructing a box in the shape of a cube is
directly proportional to its volume. If it costs P10.80 to
construct a box that is 3m by 3m by 3m, how much will it
cost to construct a box that is 2m by 2m by 2m?
6. If (𝑀 + 1) varies directly as 𝑁2
and 𝑀=17 WHEN
𝑁=3,
FIND M AND n.
7.
8. Set a Set b
1. If y varies directly as x,
and y=16 when x=5
find y when x=260
Quiz 1
2. The cost of material (C ) in
pesos is directly proportional
to the length (L) .
If 2 meters costs, P43.00
how much is the cost for 6.5
meters?
1. If y varies directly as x,
and y=16 when x=4
find y when x=231
2. The cost of material (C ) in
pesos is directly proportional
to the length (L) .
If 3 meters costs, P46.00
how much is the cost for 7.8
meters?
9.
10. Set a Set b
1. y=832
Quiz 1
2. P139.75
1. 924
2. P119.60
