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3 years ago

Prove that if xy > 0, then either x > 0 and y > 0 or x < 0 and y < 0

Mathematics

1 answer:

Rufina [12.5K]3 years ago

7 0

The rule of product states that:

$(+) \cdot (+) = (+)$
$(+) \cdot (-) = (-)$
$(-) \cdot (+) = (-)$
$(-) \cdot (-) = (+)$

So, a product is positive if and only if both factors have the same sign, and is negative if only if the factors have opposite sign.

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Sedbober [7]

Answer:

2 10 8

Step-by-step explanation:

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3 years ago

Simplify the expression<br>5-2(9)|+9^2÷3

Delicious77 [7]

Answer:

Step-by-step explanation:

Simplify the following:

5 - 2×9 + 9^2/3

Hint: | Evaluate 9^2.

9^2 = 81:

5 - 2×9 + 81/3

Hint: | Reduce 81/3 to lowest terms. Start by finding the GCD of 81 and 3.

The gcd of 81 and 3 is 3, so 81/3 = (3×27)/(3×1) = 3/3×27 = 27:

5 - 2×9 + 27

Hint: | Multiply -2 and 9 together.

-2×9 = -18:

5 + -18 + 27

Hint: | Evaluate 5 + 27 using long addition.

| 1 |

| 2 | 7

+ | | 5

| 3 | 2:

32 - 18

Hint: | Subtract 18 from 32.

| 2 | 12

| 3 | 2

- | 1 | 8

| 1 | 4:

Answer: 14

5 0

3 years ago

The table below shows how many millilitres are on different numbers of liters Mark all of the true statements

Papessa [141]

the only true statement is

in 4 liters there are 4000 milliliters

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1 year ago

Civil an airport, a factory, and a shopping center are at the vertices of a right triangle formed by three highways. the airport

vekshin1

Answer:

<em>The shortest possible length for the service road is 2.88 miles.</em>

Step-by-step explanation:

According to the below diagram, $A, B$ and $C$ are the positions of airport, shopping center and factory respectively.

Given that, $AB= 3.6 miles, BC= 4.8 miles$ and $AC= 6.0 miles$

In right triangle $ABC$

$tan(\angle ACB)=\frac{AB}{BC} \\ \\ tan(\angle ACB)= \frac{3.6}{4.8}=0.75\\ \\ \angle ACB= tan^-^1(0.75)=36.8698.... degree$

The shortest possible length for the service road from the shopping center to the highway that connects the airport and factory is $BD$ .

That means, $\triangle BCD$ is also a right triangle in which $\angle BDC=90\°$ , Hypotenuse $(BC)= 4.8$ miles and $BD$ is the opposite side in respect of $\angle DCB$ or $\angle ACB$ .

Now in right triangle $BCD$

$Sin(\angle ACB)=\frac{BD}{BC}\\ \\ Sin(36.8698...)=\frac{BD}{4.8}\\ \\ BD=4.8*Sin(36.8698...)=2.88$

So, the shortest possible length for the service road is 2.88 miles.

4 0

3 years ago

Please help ill give brainliest

maks197457 [2]

Answer:

divide by -3 and reverse it

Step-by-step explanation:

Trust me I got u fam

3 0

2 years ago

Read 2 more answers