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3 years ago

Why does a negative times a negative equal a positive proof?

Mathematics

2 answers:

lisov135 [29]3 years ago

6 0

Because two negatives cancel each other out, resulting in a positive.

lorasvet [3.4K]3 years ago

4 0

The system is two negatives cancel each other out, resulting in a positive.

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Find the unit rate- someone plzzz help me and hurryyyyy

jasenka [17]

Answer:

120 per calories I believe

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3 years ago

Guys i need help please

klio [65]

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2 years ago

A group of employees is stranded on top of a 120 feet building because a fire occurred. Your goal is to throw a rope from a 60 f

Paul [167]

Step-by-step explanation:

-16t² + 64t + 60 = 120

this is a quadratic equation, and its points of f(t) = 0 can be calculated. there are usual 2 such solutions for a quadratic equation.

so, we need to bring it to a form that ends in "= 0".

-16t² + 64t - 60 = 0

that is also the same as

-4t² + 16t - 15 = 0

the formula for the solutions of such a quadratic equation is

x = (-b ± sqrt(b² - 4ac))/(2a)

a = -4

b = 16

c = -15

so,

t = (-16 ± sqrt(256 - 4×-4×-15))/(2×-4) =

= (-16 ± sqrt(256 - 240))/-8 =

= (-16 ± sqrt(16))/-8 = (-16 ± 4)/-8

t1 = (-16 + 4)/-8 = -12/-8 = 3/2

t2 = (-16 - 4)/-8 = -20/-8 = 5/2

so, it depends on what the unit of time t is. let's assume seconds.

therefore, the rope will reach the top of the building while going up after 3/2 = 1 1/2 = 1.5 seconds.

and then, as the shot rope makes a curve and comes back down again (that is why we have 2 solutions : the rope will reach the height of 120ft during its flight path twice : once while still going up, and once when coming back down again) it will be at the height of the top of the building after 5/2 = 2 1/2 = 2.5 seconds.

so, it depends if the people there can grab it at the first chance, and if the path of the rope would allow them to grab it also again on its way back down. this we don't know.

I therefore guess, that your teacher is aiming for the first solution.

4 0

3 years ago

34xy

mr Goodwill [35]

3/4, x, and y that is the answer

6 0

3 years ago

Read 2 more answers

In a random sample of students who took the SAT test, 427 had paid for coaching courses and the remaining 2733 had not. Calculat

Dvinal [7]

Answer:

The 95% confidence interval for the proportion of students who get coaching on the SAT is (0.1232, 0.147).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.