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3 years ago

Why do you cross-multiply when you solve proportions?

Mathematics

2 answers:

olga55 [171]3 years ago

4 0

Answer:

Step-by-step explanation:

since the cross multiples are equal, you find a product and use the inverse operation as you would in an equation

Example 4 is to 36 as 3 is to X: 4/36 = 3/X --> 4*X = 3*36. Divide both sides by 4, to solve for X = 27.

is over of = percent of 100

is/of=%/100

What is 10% of 40.

is = x

x/40 = 10/100

cross mulitply 40*10= 400/100=4 x=4

Dmitriy789 [7]3 years ago

3 0

When students cross multiply while solving a proportion, they are really multiplying both sides of the equation by the products of the two denominators. What happens is that each denominator cancels one of the factors on each side, so that it seems as if you have just crossed multiplied

Hope this helps!

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14. Solve the following equations. (a), 7x + 8 = 10 + 3x

3241004551 [841]

answer: x = 1/2

explanation

subtract 3x from both sides

4x+8=10

subtract 8 from both sides

4x=2

divide both sides by 4

x=2/4

simplify

x=1/2 OR x=.5

hope i helped!

4 0

3 years ago

Read 2 more answers

Write an equation for the description

Nezavi [6.7K]

Answer:

She needs $55 more dollars

Step-by-step explanation:

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3 years ago

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Which of these professionals most directly uses geometry?

notka56 [123]

Good Morning!
air traffic controller


The most cited professional who uses geometry is the air traffic controller. This professional needs to calculate routes, distances and times traveled in order to avoid accumulation of aircraft at the time of landing, for example.

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3 years ago

You are jumping off the 12 foot diving board at the municipal pool. You bounce up at 6 feet per second and drop to the water you

NARA [144]

Answer:

When do you hit the water?

1.075 seconds after you jump.

What is your maximum height?

the maximum height is 12.5626 ft

Step-by-step explanation:

The equation:

h(t) = -16*t^2 + 6*t + 12

Is the height as a function of time.

We know that the initial height is the height when t = 0s

h(0s) = 12

and we know that the diving board is 12 foot tall.

Then the zero in h(t)

h(t) = 0

Represents the surface of the water.

When do you hit the water?

Here we just need to find the value of t such that:

h(t) = 0 = -16*t^2 + 6*t + 12

Using the Bhaskara's formula, we get:

$t = \frac{-6 \pm \sqrt{6^2 - 4*(-16)*12} }{2*(-16)} = \frac{-6 \pm 28.4}{-32}$

Then we have two solutions, and we only care for the positive solution (because the negative time happens before the jump, so that solution can be discarded)

The positive solution is:

t = (-6 - 28.4)/-32 = 1.075

So you hit the water 1.075 seconds after you jump.

What is your maximum height?

The height equation is a quadratic equation with a negative leading coefficient, then the maximum of this parabola is at the vertex.

We know that the vertex of a general quadratic:

a*x^2 + b*x + c

is at

x = -b/2a

Then in the case of our equation:

h(t) = -16*t^2 + 6*t + 12

The vertex is at:

t = -6/(2*-16) = 6/32 = 0.1875

Evaluating the height equation in that time will give us the maximum height, which is:

h(0.1875) = -16*(0.1875 )^2 + 6*(0.1875) + 12 = 12.5626

And the height is in feet, then the maximum height is 12.5626 ft

6 0

3 years ago

Jennifer has a taco stand.she found that her daily costs can be modeled by C(x)=x^2-40x+610. if she wants to keep her daily cost

polet [3.4K]

Let's focus on the given equation. The C represents the cost, while the x must be the number of tacos, which is what we're solving for. Since we're given the boundary that C must be 300, then the solution would be:

300 = x² - 40x + 610
x² - 40x + 310 = 0

Apply the quadratic formula where a = 1, b = -40 and c = 310. The roots of x are:
x = 29.49≈30
x = 10.51≈11

Thus, she needs to sell either 30 or 11 tacos.

4 0

3 years ago