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2 years ago

What is the product of (x+9)(x-9)

Mathematics

2 answers:

Verdich [7]2 years ago

8 0

Answer:

x^2 - 81

Step-by-step explanation:

There is a formula called the difference of squares, which is

(a+b)(a-b) = a^2 - b^2

ivolga24 [154]2 years ago

6 0

Answer: 9x²-81x

Step-by-step explanation:

1. Reorder the terms like this: (9x)• (x-9)

2. Remove unnecessary Parentheses like this: 9x•(x-9)

3. Distribute 9x through the Parentheses like this:

9x would become 9x² (because I combined 9x and 9x which become 9x²)

(x-9) would become -81x (so if you need further explanation I took the (x-9) and made it -9x then multiplied it by the 9x because of distributive property.)

The solution: 9x²-81x

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Please answer this question only if you know the answer!

Feliz [49]

Answer:

b. 6 cm

Step-by-step explanation:

Q is the midpoint of PR, so QR = PR/2 = (12 cm)/2 = 6 cm

7 0

2 years ago

Write an equation of the circle with center , −45 and radius 6 .

IceJOKER [234]

The general equation for a circle, $x^2+y^2=1$ , falls out of the Pythagorean Theorem, which states that the square of the hypotenuse of a right triangle is always equal to the sum of the squares of its legs (you might have seen this fact written like $a^2+b^2=c^2$ , where a and b are the legs of a right triangle and c is its hypotenuse. When we fix c in place and let a and b vary (in a sense, at least; their values are still dependent on c), the shape swept out by all of those possible triangles is a circle - a shape defined by having all of its points equidistant from some center.

How do we modify this equation to shift the circle and change its radius, then? Well, if we want to change the radius, we simply have to change the hypotenuse of the triangle that's sweeping out the circle in the first place. The default for a circle is 1, but we're looking for a radius of 6, so our equation, in line with Pythagorus's, would look like $x^2+y^2=6^2$ , or $x^{2} +y^2=36$ .

Shifting the center of the circle is a bit of a longer story, but - at first counterintuitively - you can move a circle's center to the point (a,b) by altering the x and y portions of the equation to read:

$(x-a)^2+(y-b)^2$

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2 years ago

What the hell WHERES THE NUMBERS TO THE VARIABLE

Svetradugi [14.3K]

Answer:

$t=\frac{d}{r}$

There are no numbers because it is changing the subject of the equation.

Step-by-step explanation:

$d=rt$

$\frac{d}{r} =t$

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2 years ago

14 over 21 simplified

anastassius [24]

2 over 3 is 14 over 21 simplified, dividing both numbers by 7.

4 0

3 years ago

Read 2 more answers

According to a poll, 55 % of Americans do not know that GOP stands for Grand Old Party (Time, October 17, 2011). Assume that thi

Ivenika [448]

Answer:

$\hat p \sim N (p , \sqrt{\frac{p(1-p)}{n}})$

The mean is given by:

$\mu_{\hat p} = 0.55$

And the deviation:

$\sigma_{\hat p} =\sqrt{\frac{0.55*(1-0.55)}{953}}= 0.0161$

Step-by-step explanation:

For this case we assume that the true population proportion of Americans do not know that GOP stands for Grand Old Party is 0.55 and we select a random sample of n = 953 americans

For this case we assume that we satisfy the conditions to use the normal approximation for $\hat p$

1) np >10 , n(1-p)>10

2) Independence

3) Random sample

4) The sample size is less than 10% of the population size

We assume that all the conditions are satisfied and the distribution for $\hat p$ would be:

$\hat p \sim N (p , \sqrt{\frac{p(1-p)}{n}})$

The mean is given by:

$\mu_{\hat p} = 0.55$

And the deviation:

$\sigma_{\hat p} =\sqrt{\frac{0.55*(1-0.55)}{953}}= 0.0161$

3 0

2 years ago