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Mkey [24]
3 years ago
5

The 10th term of an a.p is -27 and the 5th term is -12 .find the first term?​

Mathematics
1 answer:
horsena [70]3 years ago
3 0

Step-by-step explanation:

a_{10} = - 27... (Given) \\\\\therefore a + 9d = - 27...... (1)\\\\a_{5} = - 12... (Given) \\\\\therefore a + 4d = - 12.......(2)\\\\

Subtracting equation (2) from equation (1)

a + 9d-( a + 4d )= - 27-(-12)\\\\\therefore a +9d - a-4d = - 27+12\\\\\therefore 5d = - 15\\\\\therefore d = \frac {- 15}{5}\\\\\huge \orange {\boxed {\therefore d = -3}} \\\\

Substituting d = - 3 in equation (1), we find:

a + 9\times (-3)= - 27\\\\\therefore a - 27 = - 27\\\\\therefore a  = 27- 27\\\\\huge \red {\boxed {\therefore a  = 0}}\\\\

Hence, first term is zero.

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Fraction : 3/11+7/15= <br> Please show me how you got the answer
avanturin [10]
So the first thing you would have to is to find a common denominator so a common denominator between 11 and 15 is 165. 3/11 * 15 =45/165  next you would do 7/15 * 11=77/165 no that both denominators are the same we add the numerator but the denominator stays the same so 45/165 + 77/165 = 122/165
and since it can't be reduced any more 122/165 is your answer. 

hope this helps :)

5 0
3 years ago
Dubnium-262 has a half-life of 34 s. How long will it take for 500.0 grams to
dmitriy555 [2]

Answer:

the time taken for the radioactive element to decay to 1 g is 304.8 s.

Step-by-step explanation:

Given;

half-life of the given Dubnium = 34 s

initial mass of the given Dubnium, m₀ = 500 grams

final mass of the element, mf = 1 g

The time taken for the radioactive element to decay to its final mass is calculated as follows;

1 = 500 (0.5)^{\frac{t}{34}} \\\\\frac{1}{500} =  (0.5)^{\frac{t}{34}}\\\\log(\frac{1}{500}) = log [(0.5)^{\frac{t}{34}}]\\\\log(\frac{1}{500})  = \frac{t}{34} log(0.5)\\\\-2.699 = \frac{t}{34} (-0.301)\\\\t = \frac{2.699 \times 34}{0.301} \\\\t = 304.8 \ s

Therefore, the time taken for the radioactive element to decay to 1 g is 304.8 s.

4 0
2 years ago
louise bought 80 metres of fencing to make an enclosure for her pet dog .tommy if louise expects a rectangular enclosure what is
OleMash [197]

Answer:

400 m^2.

Step-by-step explanation:

The largest  area is obtained where the enclosure is a square.

I think that's the right answer because a square is a special form of a rectangle.

So the square would be 20 * 20  = 400 m^2.

Proof:

Let the  sides of the rectangle be x and y m long

The area A = xy.

Also the perimeter  2x + 2y = 80

x + y = 40

y = 40 - x.

So substituting for y in A = xy:-

A = x(40 - x)

A = 40x - x^2

For maximum value of A  we find the derivative and equate it to 0:

derivative A' =  40 - 2x = 0

2x = 40

x = 20.

So y = 40 - x

= 40 - 20

=20  

x and y are the same value so x = y.

Therefore for maximum area the rectangle is a square.

3 0
3 years ago
Josiah is buying a Christmas present for his mom. He has $24 in his saving account but needs $60 to buy the present he has in mi
olchik [2.2K]

Answer:

Step-by-step explanation:

9h + 24 = 60

6 0
2 years ago
WILL GIVE BRAINLIST IF ANSWER IS CORRECT!
ella [17]

Answer: its is square pyramid or D

Step-by-step explanation:

5 0
3 years ago
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