Answer:
10⁴ seconds
Step-by-step explanation:
Given that,
A person breathes 
in about cubic meters of air per second.
We need to find time taken to breathe 2.5 cubic meters of air.
In 1 sec = m³ of air breathe
Let in x seconds, 2.5 m³ of air taken by the person.
Hence, in 10⁴ seconds 2.5 m³ of air is taken by the person.
The maximum possible volume of this type of box that can be made from a 20 cm by 20 cm square of paper is 512cm³.
<h3>How to calculate the volume?</h3>
From the information, when the side of 1cm are cut, this will become an open box. The volume will be:
= 18 × 18 × 1
= 324cm³
Also, when 2cm is cut, the volume will be:
= 16 × 16 × 2
= 512cm³
Learn more about volume on:
brainly.com/question/1972490
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<u>Question 8</u>
a^2 + 7a + 12
= (a+3)(a+4)
When factorising a quadratic, the product of the two factors should equal the constant term (12), and the sum of the two factors should equal the linear term (7). To find the two factors, list out the factors of 12 (1x12, 2x6, 3x4) and identify the pair that adds up to 7 (3+4).
An alternative method if you get stuck during your exam would be to solve it algebraically using the quadratic formula and then write it in the factorised form.
a = (-7 +or- sqrt(7^2 - 4(1)(12)) / 2(1)
= (-7 +or- sqrt(1))/2
= -3 or -4
These factors are the negative of the values that would go in the brackets when written in factorised form, as when a = -3 the factor (a+3) would equal 0. (If it were positive 3 instead, then in the factorised form it would be a-3).
<u>Question 10</u>
-3(x - y)/9 + (4x - 7y)/2 - (x + y)/18
Rewrite each fraction with a common denominator so you can combine the fractions into one.
= -6(x - y)/18 + 9(4x - 7y)/18 - (x + y)/18
= (-6(x - y) + 9(4x - 7y) - (x + y)) /18
Expand the brackets and collect like terms.
= (-6x + 6y + 36x - 63y - x - y)/18
= (29x - 58y)/18
= 29/18 x - 29/9 y
Answer:
The mistake she made was ; She didn't change the sign when subtracting -3/4 from both sides
She wrote 5/4+3/4 instead of 5/4-3/4
Step-by-step explanation:
Correct solution:
Subtract-3/4 from both sides
Simplify
Answer:
5 4/5
Step-by-step explanation:
First of all subtract the whole number, 2, from 8 1/5
You would get 6 1/5
Now subtract 2/5 from that, or set up an equation like:
6 + 1/5 - 2/5
you would get 6 - 1/5 or 5 4/5
-Chetan K
