A. PreliminariesDirections: If the statement “y varies jointly with respect to x
and z” and the equation is in the form “y = kxz” (where k is
the constant), translate each statement into a mathematical
sentence using this pattern.
1. s varies jointly as r and t
2. V varies jointly as l, w, and h
3. N varies jointly as 𝑀1 and 𝑀2
4. A varies jointly as b and the square of c
5. The electrical voltage V varies jointly as the current I and
the resistance R.
Joint
Variations
Joint Variation is the same as direct
variation with two or more
variables. The statement “a varies
jointly as b and c” means a = kbc, or
𝒌 =
𝒂
𝒃𝒄
where k is the constant of
variation.
Illustrative Example 1:
The pressure P of gas varies jointly
as its density D, and its absolute
temperature T.
Solutions:
P = kDT where k is the constant of
variation
2. Find an equation of variation where a varies
jointly as b and c, and a = 24 when b = 2 and c =
3.
Solutions:
A = kbc
24 = k(2)(3)
24 = 6k
k = 4 Therefore, a = 4bc is the required
equation of variation.
3. The area of a rectangle varies jointly as the
length and the width, and whose A = 72 sq. cm
when l = 12 cm and w = 2cm. Find the area of
the rectangle whose length is 15 cm and whose
width is 3 cm.
Solutions: A = klw
72 = k(12)(2)
72 = 24k
k = 3
Therefore, when l = 15 cm
and w = 3 cm,
A = klw
A = 3(15)(3)
A = 135 sq.cm
a. What is joint
variation?
b. How do we transform
mathematical
statement in joint
variation equation?
Directions: Solve for the value of the constant k of
variation, then find the missing value.
1. If y varies jointly as the product of x and z, and y =
105 when x = 5 and z = 7, find y when x = 9 and z =
10.
2. If y varies jointly as the product of x and z, and y =
1000 when x = 10 and z = 20, find y when x = 8 and
z = 10.
3. A varies jointly with l and w, when A = 24, l = 3 and
w = 2. Find A when l = 12 and w = 7
1.y=270
2.y=360
3.A=336
Exercise #2.__. Directions: Solve the
following and BOX your final answer
1. y varies jointly as x and z, find y
if x =3, k = 6 and z = 9
2. c varies jointly as a and b. If c =
45 when a = 15 and b = 3, find c
when a = 21 and b = 8.
1. m varies jointly as n and p. If p =
4 when m = 72 and n = 2, find p
when m = 12 and n = 8.
2. q varies jointly as g and the
square of b. If q = 105 when g =
14 and b = 5, find q when g = 10
and b = 14
3.
4.
1. y =162
2. c = 168
3. p =
𝟏
𝟔
4. q = 588
Joint Variation is the same as direct
variation with two or more
variables. The statement “a varies
jointly as b and c” means a = kbc, or
𝒌 =
𝒂
𝒃𝒄
where k is the constant of
variation.
Assignment # 2. Solve:
1. z varies jointly with x and y. If x=2, y=3
and z=4, write the variation equation and
find z when x=−6 and y=2.
2. z varies jointly with x and y. If x=5, y=−1
and z=10, write the variation equation and
find z when x=−12 and y=7.
3. z varies jointly with x and y. If x=7, y=3 and
z=−14, write the variation equation and find z
when x=8 and y=3
4.Study
a. What do you mean by the word combined?
b. What is combined variation?
c. What mathematical statement represents
combined variation?
1.
2.
3.

joint variation

  • 1.
    A. PreliminariesDirections: Ifthe statement “y varies jointly with respect to x and z” and the equation is in the form “y = kxz” (where k is the constant), translate each statement into a mathematical sentence using this pattern. 1. s varies jointly as r and t 2. V varies jointly as l, w, and h 3. N varies jointly as 𝑀1 and 𝑀2 4. A varies jointly as b and the square of c 5. The electrical voltage V varies jointly as the current I and the resistance R.
  • 2.
  • 3.
    Joint Variation isthe same as direct variation with two or more variables. The statement “a varies jointly as b and c” means a = kbc, or 𝒌 = 𝒂 𝒃𝒄 where k is the constant of variation.
  • 4.
    Illustrative Example 1: Thepressure P of gas varies jointly as its density D, and its absolute temperature T. Solutions: P = kDT where k is the constant of variation
  • 5.
    2. Find anequation of variation where a varies jointly as b and c, and a = 24 when b = 2 and c = 3. Solutions: A = kbc 24 = k(2)(3) 24 = 6k k = 4 Therefore, a = 4bc is the required equation of variation.
  • 6.
    3. The areaof a rectangle varies jointly as the length and the width, and whose A = 72 sq. cm when l = 12 cm and w = 2cm. Find the area of the rectangle whose length is 15 cm and whose width is 3 cm. Solutions: A = klw 72 = k(12)(2) 72 = 24k k = 3 Therefore, when l = 15 cm and w = 3 cm, A = klw A = 3(15)(3) A = 135 sq.cm
  • 7.
    a. What isjoint variation?
  • 8.
    b. How dowe transform mathematical statement in joint variation equation?
  • 9.
    Directions: Solve forthe value of the constant k of variation, then find the missing value. 1. If y varies jointly as the product of x and z, and y = 105 when x = 5 and z = 7, find y when x = 9 and z = 10. 2. If y varies jointly as the product of x and z, and y = 1000 when x = 10 and z = 20, find y when x = 8 and z = 10. 3. A varies jointly with l and w, when A = 24, l = 3 and w = 2. Find A when l = 12 and w = 7
  • 10.
  • 11.
    Exercise #2.__. Directions:Solve the following and BOX your final answer 1. y varies jointly as x and z, find y if x =3, k = 6 and z = 9 2. c varies jointly as a and b. If c = 45 when a = 15 and b = 3, find c when a = 21 and b = 8.
  • 12.
    1. m variesjointly as n and p. If p = 4 when m = 72 and n = 2, find p when m = 12 and n = 8. 2. q varies jointly as g and the square of b. If q = 105 when g = 14 and b = 5, find q when g = 10 and b = 14 3. 4.
  • 13.
    1. y =162 2.c = 168 3. p = 𝟏 𝟔 4. q = 588
  • 14.
    Joint Variation isthe same as direct variation with two or more variables. The statement “a varies jointly as b and c” means a = kbc, or 𝒌 = 𝒂 𝒃𝒄 where k is the constant of variation.
  • 15.
    Assignment # 2.Solve: 1. z varies jointly with x and y. If x=2, y=3 and z=4, write the variation equation and find z when x=−6 and y=2. 2. z varies jointly with x and y. If x=5, y=−1 and z=10, write the variation equation and find z when x=−12 and y=7.
  • 16.
    3. z variesjointly with x and y. If x=7, y=3 and z=−14, write the variation equation and find z when x=8 and y=3 4.Study a. What do you mean by the word combined? b. What is combined variation? c. What mathematical statement represents combined variation?
  • 17.