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Paladinen [302]
2 years ago
14

The length of a rectangle is 5 cm more than twice a number. the width is 4cm less than the same number. if the area of the recta

ngle is 15cm2, find the number
​
Mathematics
1 answer:
lana [24]2 years ago
7 0
A = Lw (area of rectangle is length times width)
A = 15 (Area is 15)
L = 2x + 5 (length is 2 times a number plus another 5)
w = x - 4 (width is 4 less than that number

Plug in the values:
15 = (2x + 5)(x - 4)
FOIL
15 = 2x2 - 8x + 5x - 20
simplify:
15 = 2x2 - 3x - 20
Subtract 15
0 = 2x2 - 3x - 35
Factor out the quadratic. We know that one number has to be 7 and the other 5 so that they multiply together to make 35, and that one of them has to be negative so that it's actually -35.
That means we have m * n = -35
We also need it set up so that so that 2m + n = -3:
2 * -5 + 7 = -3
0 = (2x + 7)(x - 5)
So:
0 = 2x + 7, or 0 = x - 5
x = -7/2 or 5
We cannot have a negative length, so x = 5

Check:
15 = (2 * 5 + 5) (5 - 4)
15 = 15 * 1
15 = 15
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Contact [7]

Answer:

V-9%= Vehicles Left  V- 0.09= Vehicles Left

Step-by-step explanation:

3 0
3 years ago
Fiona and Camilla took a load of peaches to the farmer’s market. During the first hour, they sold ½ of the peaches plus ½ of a p
Lana71 [14]
<em>They took 101 peaches to market.</em>

<u>Check:</u>

In the 1st hour, they sold (101/2 + 1/2) = 102/2 = 51.  They had 50 left.

In the 2nd hour, they sold (50/3 + 1/3)=51/3=17.  They had (50-17)=33 left.

In the 3rd hour, they sold (33/4 + 3/4) = 36/4 = 9.  They had (33-9) = 24 left.

In the final hour, they sold (24/5 + 1/5) = 25/5 = 5.  They had (24-5) = 19 left.  yay!

Fiona and Camilla took their 19 remaining peaches and went home.  Sharing with
their parents and their brother Rowlf, each person had 3.8 peaches for dinner.
There was a lot of activity in the bathroom overnight.

================================================

The key to solving this one is to work it backwards.

-- They had 19 peaches left at the end of the day.

-- During the final hour, the 1/5 of a peach that they sold left them with 19,
so they had 19-1/5 before they sold the 1/5 of a peach.
The 19-1/5 was 4/5 of what they had at the beginning of the final hour.
So, at the beginning of the final hour, they had (5/4)x(19.2) = 24 .

-- During the 3rd hour, the 3/4 of a peach that they sold left them with 24,
so they had 24-3/4 before they sold the 3/4 of a peach.
The 24-3/4 was 3/4 of what they had at the beginning of that hour.
So, at the beginning of the 3rd hour, they had (4/3)x(24.75) = 33 .

Do the same for the 2nd hour.

Then do the same for the 1st hour.

And you'll work your way back up to 101 peaches.


4 0
3 years ago
What is 299,864 times 5?
irakobra [83]

Answer:

1,498,420

Step-by-step explanation:

6 0
3 years ago
A circle has a radius of 30 cm.
topjm [15]
It would be 60 because all you do is double the radius because it is only half of the circle
4 0
2 years ago
Read 2 more answers
The sum of 3 times a number and 7 is 25
hammer [34]

Mathematically written:

3 * x + 7 = 25

3x + 7 = 25

3x = 25 - 7

3x = 18

x = 18 / 3

x = 6



Proof:

3 * 6 + 7 = 25

18 + 7 = 25

25 = 25 → both sides of the equation are equal, our answer is correct



Notes:

A number - Is an unknown number, called a variable, which in this case is substituted by the letter x.





Hope it helped,




BioTeacher101


5 0
3 years ago
Read 2 more answers
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