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3 years ago

Find the percent decrease, round to the nearest percent from 39 seconds to 13 seconds

Mathematics

1 answer:

andrew11 [14]3 years ago

3 0

Answer:12

Explaination:

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How can i prove this property to be true for all values of n, using mathematical induction.

chubhunter [2.5K]

Proof -

So, in the first part we'll verify by taking n = 1.

$\implies \: 1 = {1}^{2} = \frac{1(1 + 1)(2 + 1)}{6}$

$\implies{ \frac{1(2)(3)}{6} }$

$\implies{ 1}$

Therefore, it is true for the first part.

In the second part we will assume that,

$\: { {1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} = \frac{k(k + 1)(2k + 1)}{6} }$

and we will prove that,

$\sf{ \: { {1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{(k + 1)(k + 1 + 1) \{2(k + 1) + 1\}}{6}}}$

$\: {{1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{(k + 1)(k + 2) (2k + 3)}{6}}$

${1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{k (k + 1) (2k + 1) }{6} + \frac{(k + 1) ^{2} }{6}$

${1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{k(k+1)(2k+1)+6(k+1)^ 2 }{6}$

${1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{(k+1)\{k(2k+1)+6(k+1)\} }{6}$

${1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{(k+1)(2k^2 +k+6k+6) }{6}$

${1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{(k+1)(2k^2+7k+6) }{6}$

${1}^{2} + {2}^{2} + {3}^{2} + ..... + {k}^{2} + (k + 1)^{2} = \frac{(k+1)(k+2)(2k+3) }{6}$

<u>Henceforth, by </u><u>using </u><u>the </u><u>principle </u><u>of </u><u> mathematical induction 1²+2² +3²+....+n² = n(n+1)(2n+1)/ 6 for all positive integers n</u>.

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8 0

2 years ago

20% of Ms. Martin's class did not complete their homework. If there are 30 students in her class, how many did not complete home

padilas [110]

Answer:

Step-by-step explanation:

20% of 30 is 6

Words: 6 Students in Ms. Martin's class did not do their homework.

hope this helps :)

7 0

3 years ago

PLEASE HURRY ITS TIMED 20 POINTS!!!What is the y-coordinate of the point shown in the graph?

Drupady [299]

<h3><em>X CO-ORDINATE = 3</em></h3><h3><em>Y CO-ORDINATE = -7</em></h3><h3><em>HOPE IT HELPS.....BYE....</em></h3>

7 0

3 years ago

Read 2 more answers

Evaluate the expression 2b ^3+5 when b=3

pochemuha

Answer:

Step-by-step explanation:

b^3 is 27

2(27) is 54

54+5 is 59

if u mean (2b)^3 then 2b is 6

6^3 is 216

plus 5 is 221

3 0

3 years ago

A. 1 and 8 <br> B. 4 and 6<br> C. 5 and 6<br> D. 1 and 7 <br> Please tell me why

andre [41]

1 and 7 because they have the same angles

6 0

3 years ago