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insens350 [35]
3 years ago
5

V = 3i – 5j and w = -7i + 4j , find 3v – 4w​?

Mathematics
2 answers:
Shalnov [3]3 years ago
6 0
3v - 4w
3(3i-5j) - 4(-7i+4j)
= (9i-15j) - (-28i+16j)
Part 1) 9i - - 28i = 9i + 28i = 37i
Part 2) -15j - 16j = -31j

Answer: 37i - 31j
astraxan [27]3 years ago
4 0

Answer:

5i - 45j

Step-by-step explanation:

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how many gallons of a 50 antifreeze solution must be mixed with 90 gallons of 20% antifreeze to get a mixture that is 40% antifr
Tamiku [17]
Try this:
1) note that weight of pure antifreeze before mixing and after mixing is the same. So, if 'x' is weight of pure antifreeze in 50% solution, it is possible to make up equation before mixing: 0.5x+0.2*90.
2) there are 0.2*90=18 gal. of pure antifreeze in the 20% solution. If 'x' gal. is the weight of pure antifreeze in 50% sol. and 18 gal. is the weight of pure antifreeze in 20% sol., it is possible to make up an equation after mixing: 0.4(x+18).
3) using the both parts: 0.5x+0.2*90=0.4(x+18) ⇒ x=54 gal. of <u>pure</u> weight.
4) to find 50% solution of 54 gal. pure weight just 54:0.5=108 gal.
Answer: 108 gal.
3 0
3 years ago
Match each three-dimensional figure to its volume based on the given dimensions. (Assume π = 3.14.)
LekaFEV [45]

Answer:

The volume of the cylinder is 150.72 cm³ ⇒ last answer

The volume of the cone is 314 cm³ ⇒ 1st answer

The volume of the pyramid is 160 cm³ ⇒ 2nd answer

The volume of the pyramid is 48 cm³ ⇒ 3rd answer

Step-by-step explanation:

* Lets revise the volumes of some shapes

- The volume of the cylinder of radius r and height h is:

 V = π r² h

- The volume of the cone of radius r and height h is:

 V = 1/3 π r² h

- The volume of the pyramid is:

 V = 1/3 × its base area × its height

* Lets solve the problem

# A cylinder with radius 4 cm and height 3 cm

∵ V = π r² h

∵ π = 3.14

∵ r = 4 cm , h = 3 cm

∴ v = 3.14 (4)² (3) = 150.72 cm³

* The volume of the cylinder is 150.72 cm³

# A cone with radius 5 cm and height 12 cm

∵ V = 1/3 π r² h

∵ π = 3.14

∵ r = 5 cm , h = 12 cm

∴ V = 1/3 (3.14) (5)² (12) = 314 cm³

* The volume of the cone is 314 cm³

# A pyramid with base area 16 cm² and height 30 cm

∵  V = 1/3 × its base area × its height

∵ The area of the base is 16 cm²

∵ The height = 30 cm

∴ V = 1/3 (16) (30) = 160 cm³

* The volume of the pyramid is 160 cm³

# A pyramid with square base of length 3 cm and height 16 cm

∵  V = 1/3 × its base area × its height

∵ The area of the square = s²

∵ The area of the base = 3² = 9 cm²

∵ The height = 16 cm

∴ V = 1/3 (9) (16) = 48 cm³

* The volume of the pyramid is 48 cm³

3 0
3 years ago
Read 2 more answers
(07.01)
serg [7]
X+10=13
-10 -10
—————
x= 3

Answer is: 2) 3
3 0
3 years ago
Read 2 more answers
An algebraic expression for 2 times a number plus 5
natali 33 [55]

Answer:

2x+5

Step-by-step explanation:

X represents the number in "2 times a number." You could insert any number into x.

8 0
3 years ago
So I've got a math problem I don't understand: simplify (3^ - 2 + 5^ - 2) ^ -1 I got 34 but apparently the answer's 225/34, shou
leva [86]
The exponent tells you the number of times that factor is in the product. When the exponent is negative, the product is in the denominator.
.. (3⁻² +5⁻²)⁻¹ = 1/(1/9 +1/25) = 1/(34/225) = 225/34
3 0
3 years ago
Read 2 more answers
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