We are asked to find unknown or the missing number to complete the polynomial given in the problem which is x² + ?x -49. First, let us equate the number to be equal to zero such as it would become x² + ?x - 49 = 0. Next, we need to find the factors such that it would produce a difference of squares and these two factors are a = +7 and b = -7. Hence, the complete solution is shown below:
(x + 7) (x-7) = 0
perform distribution and multiplication of terms such as shown below:
x² + 7x - 7x - 49 = 0
Combine the same term such as we can either add or subtract +7x to -7x and the result will be equal to 0x.
x² + 0x - 49 = 0

Therefore, the missing number is 0. The answer is 0 which will result to x² +0x - 49.

4 0

3 years ago

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the height h(t) of a trianle is increasing at 2.5 cm/min, while it's area A(t) is also increasing at 4.7 cm2/min. at what rate i

nekit [7.7K]

Answer:

The base of the triangle decreases at a rate of 2.262 centimeters per minute.

Step-by-step explanation:

From Geometry we understand that area of triangle is determined by the following expression:

$A = \frac{1}{2}\cdot b\cdot h$ (Eq. 1)

Where:

$A$ - Area of the triangle, measured in square centimeters.

$b$ - Base of the triangle, measured in centimeters.

$h$ - Height of the triangle, measured in centimeters.

By Differential Calculus we deduce an expression for the rate of change of the area in time:

$\frac{dA}{dt} = \frac{1}{2}\cdot \frac{db}{dt}\cdot h + \frac{1}{2}\cdot b \cdot \frac{dh}{dt}$ (Eq. 2)

Where:

$\frac{dA}{dt}$ - Rate of change of area in time, measured in square centimeters per minute.

$\frac{db}{dt}$ - Rate of change of base in time, measured in centimeters per minute.

$\frac{dh}{dt}$ - Rate of change of height in time, measured in centimeters per minute.

Now we clear the rate of change of base in time within (Eq, 2):

$\frac{1}{2}\cdot\frac{db}{dt}\cdot h = \frac{dA}{dt}-\frac{1}{2}\cdot b\cdot \frac{dh}{dt}$

$\frac{db}{dt} = \frac{2}{h}\cdot \frac{dA}{dt} -\frac{b}{h}\cdot \frac{dh}{dt}$ (Eq. 3)

The base of the triangle can be found clearing respective variable within (Eq. 1):

$b = \frac{2\cdot A}{h}$

If we know that $A = 130\,cm^{2}$ , $h = 15\,cm$ , $\frac{dh}{dt} = 2.5\,\frac{cm}{min}$ and $\frac{dA}{dt} = 4.7\,\frac{cm^{2}}{min}$ , the rate of change of the base of the triangle in time is:

$b = \frac{2\cdot (130\,cm^{2})}{15\,cm}$

$b = 17.333\,cm$

$\frac{db}{dt} = \left(\frac{2}{15\,cm}\right)\cdot \left(4.7\,\frac{cm^{2}}{min} \right) -\left(\frac{17.333\,cm}{15\,cm} \right)\cdot \left(2.5\,\frac{cm}{min} \right)$

$\frac{db}{dt} = -2.262\,\frac{cm}{min}$

The base of the triangle decreases at a rate of 2.262 centimeters per minute.

6 0

2 years ago

Find the difference: square root of 20 - square root of 80

Mamont248 [21]

Answer:

$-2\sqrt{5}$

Step-by-step explanation:

$\sqrt{20} = \sqrt{10*2} = \sqrt{5 * 2 *2} = \sqrt{2^2 * 5} = 2\sqrt{5} \\\\\sqrt{80} = \sqrt{20*4} = \sqrt{5*4 *4} = \sqrt{4^2 * 5} = 4\sqrt{5} \\\\2\sqrt{5} - 4\sqrt{5} = -2\sqrt{5}$

8 0

2 years ago

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Isabel joins a service to download movies. She pays $2 per movie, but she gets the first 5 movies for free. How many movies, m,

Damm [24]

The first question the answer to it is 30.

To do that divide 50/2 and see how many movies she can buy, which 25, then add the 5 free movies which gives you 30.

And the second part of the question I think is missing a picture or something.

3 0

3 years ago

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