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3 years ago

The length of the rectangle is x + 12. The width of the rectangle is x + 3. Please determine the area of the rectangle.

Mathematics

1 answer:

OverLord2011 [107]3 years ago

3 0

Answer:

For part A, the product of (-5 + x)(x + 4) is equal to x^2 - x - 20. For part B, the product of -5 + x and x + 4 is not equal to the product of 5 + x and x - 4. And for part C the product of (3 + 5)(3^2 + 4 - 3) equals 70.

Step-by-step explanation:

I will tell you how I came up with those answers.

The product of (-5 + x)(x + 4) can be found using the FOIL method(First, Outer, Inner, Last).

Start with multiplying -5 and x. -5 * x = -5x.

Now multiply -5 and 4. -5 * 4 = -20.

Next, multiply x and x. x * x = x^2.

Finally, multiply x and 4. x * 4 = 4x.

And now it is time to simplify and change to standard form.

-5x - 20 + x^2 + 4x.

x^2 - 5x - 20 + 4x.

x^2 - 5x + 4x - 20.

x^2 - x - 20.

The final answer for part A is x^2 - x - 20.

For part B, the product of -5 + x and x + 4 is already known.

But now we need to figure out the product of 5 + x and x - 4.

We can use the FOIL method again to solve for the new product.

Start by multiplying 5 and x. 5 * x = 5x.

Next, multiply 5 and -4. 5 * -4 = -20.

Now multiply x and x. x * x = x^2.

Finally, multiply x and -4. x * -4 = -4x.

And now we can simplify and arrange the terms into standard form.

5x - 20 + x^2 - 4x.

x^2 + 5x - 20 - 4x.

x^2 + 5x - 4x - 20.

x^2 + x - 20.

The final answer for part B is that the products of

(-5 + x)(x + 4) and (5 + x)(x - 4) are not equivalent. They look similar except the difference between them is the "x" value. The x value of the first equation's product is -x while the x value of the second equation's product is x.

For part C, use the FOIL method as used in the last questions to find the answer.

2 * 3^2 = 2 * 9 = 18.

2 * 4 = 8.

2 * -3 = -6.

5 * 3^2 = 5 * 9 = 45.

5 * 4 = 20.

5 * -3 = -15.

Now combine the numbers to get the final answer for part C.

Follow PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition and Subtraction).

The only operations are subtraction and addition. The rule is the add before subtracting, but this does not always apply. For this being true, we only need to perform the first operation from the left side.

18 + 8 - 6 + 45 + 20 - 15.

26 - 6 + 45 + 20 - 15.

20 + 45 + 20 - 15.

65 + 20 - 15.

85 - 15.

70.

So the last answer to part C is 70.

Also the area of the rectangle is x^2 + 15x + 36. I forgot that part, my apologies.

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The change in water level of a lake is modeled by a polynomial function, W(x). Describe how to find the x-intercepts of W(x) and

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First. Finding the x-intercepts of $W(x)$

Let $W(x)$ be the change in water level. So to find the x-intercepts of this function we can use The Rational Zero Test that states:

To find the zeros of the polynomial:

$f(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+...+a_{2}x^{2}+a_{1}x+a_{0}$

We use the Trial-and-Error Method which states that a factor of the constant term:

$a_{0}$

can be a zero of a polynomial (the x-intercepts).

So let's use an example: Suppose you have the following polynomial:

$W(x)=x^{4}-x^{3}-7x^{2}+x+6$

where the constant term is $a_{0}=6$ . The possible zeros are the factors of this term, that is:

$1, -1, 2, -2, 3, -3, 6 \ and \ -6$ .

Thus:

 $W(1)=0 \\ W(-1)=0 \\ W(2)=-12 \\ W(-2)=0 \\ W(3)=0 \\ W(-3)=48 \\ W(6)=840 \\ W(-6)=1260$ 

From the foregoing, we can affirm that $1, -1, -2 \ and \ 3$ are zeros of the polynomial.

Second. Construction a rough graph of $W(x)$

Given that this is a polynomial, then the function is continuous. To graph it we set the roots on the coordinate system. We take the interval:

$[-2,-1]$

and compute $W(c)$ where $c$ is a real number between -2 and -1. If $W(c)>0$ , the curve start rising, if not, the curve start falling. For instance:

$If \ c=-\frac{3}{2} \\ \\ then \ w(-\frac{3}{2})=-2.81$

Therefore the curve start falling and it goes up and down until $x=3$ and from this point it rises without a bound as shown in the figure below