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3 years ago

The length of a rectangular piece of land is 9 cm more than 3 times its width. The perimeter is 418 cm. Find its dimensions.

1 answer:

3 0

Let w represent the width of the rectangle in cm. Then its length in cm is (3w+9). The perimeter is the sum of two lengths and two widths, so is ...

... 418 = 2(w + (3w+9))

... 209 = 4w +9 . . . . . . divide by 2, collect terms

... 200 = 4w . . . . . . . . subtract 9

... 50 = w . . . . . . . . . . divide by 4

... length = 3w+9 = 3·50 +9 = 159

The dimensions of this piece of land are 159 cm by 50 cm.

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What 2 numbers multiply to be -14 and add to be -3

Svetach [21]

Xy = -14
x + y = -3

$xy = -14$
$\frac{xy}{x} = \frac{-14}{x}$
$y = \frac{-14}{x}$

$x + y = -3$
$x + \frac{-14}{x} = -3$
$\frac{x^{2}}{x} + \frac{-14}{x} = -3$
$\frac{x^{2} - 14}{x} = -3$
$x^{2} - 14 = -3x$
$x^{2} + 3x - 14 = 0$
$x = \frac{-(3) \± \sqrt{(3)^{2} - 4(1)(-14)}}{2(1)}$
$x = \frac{-3 \± \sqrt{9 + 56}}{2}$
$x = \frac{-3 \± \sqrt{65}}{2}$
$x = \frac{-3 \± 8.06}{2}$
$x = -1.5 \± 4.03$
$x = -1.5 + 4.03$ $or$ $x = -1.5 - 4.03$
$x = 2.53$ $or$ $x = -5.53$

  x + y = -3
2.53 + y = -3
- 2.53 - 2.53
  y = -5.53
  (x, y) = (2.53, -5.53)

x + y = -3
  -5.53 + y = -3
+ 5.53   + 5.53
  y = 2.53
  (x, y) = (-5.53, 2.53)

The two numbers that multiply to -14 and add up to -3 are -5.53 and 2.53.

8 0

3 years ago

The expression 2(128 + 5) + V7 can be used to find the perimeter of the triangle. What does

Mama L [17]

You do the things in the parentheses first then multiply them by 2

5 0

3 years ago

The weights of red delicious apples are approximately normally distributed with a mean of 9 Ounces and a standard deviation of 0

Simora [160]

Answer:

The mean of W is 55 ounces.

The standard deviation of W is 4.33 ounces.

Step-by-step explanation:

Let X: weight of a red delicious apple, and B: the weight of the box and packing material.

The distribution that will represent W: the total weight of the packaged 5 randomly selected apples will be also normally distributed.

Applying the property of the mean: $E(aX)=aE(X)$ , the mean of W will be:

$\mu_W=E(W)=E(5X+B)=5E(X)+E(B)=5*9+10=45+10=55$

Applying the property of the variance: $V(aX+b)=a^2V(X)$ , the variance of W will be:

$\sigma^2_W=V(W)=V(5X+B)=5^2V(X)+V(B)=25*0.75+0=18.75$

The mean standard deviation of W will be the squared root of V(W):

$\sigma_W=\sqrt{V(W)}=\sqrt{18.75}=4.33$

The mean of W is 55 ounces.

The standard deviation of W is 4.33 ounces.

3 0

4 years ago

SomeOne Do This Thank You If u had because if u answered my question u get.................................................... i

jonny [76]

Answer:

Step-by-step explanation:

By gradient, if you mean the "slope" of the linear function, then you have to find two points of the graph and use the "rise over run strategy". Given two coordinates, (x1, y1) and (x2, y2) of a linear function in the form y=mx+b, the slope of the line is (y2-y1)/(x2-x1). This shows the amount of "rise", or the vertical change, and the amount of "run", which is the horizontal change. Rise/Run gives the steepness of the line. The slope can also be modeled by Δy/Δx, which is the change in y over the change in x

Plugging in the given points (0,5) and (-5,0):

(y2-y1)/(x2-x1)= (5-0)/(0-(-5)) = 5/5 = 1

7 0

3 years ago

Can someone help me with this math homework please!

Assoli18 [71]

1. a= 19

2.2 ( second option)

3.C

7 0

3 years ago