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3 years ago

9

Lolz please help me I would gladly appreciate it

2 answers:

Tanzania [10]3 years ago

6 0

Pentagon has sum of 540°

Alisiya [41]3 years ago

5 0

Has the sum of 540 degrees

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0.52+0.15=0.52+x????

pychu [463]

What I did is to add 0.52
+0.15
then try to find what could equal the same amount with 0.52

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3 years ago

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Which equation has a solution of t = 1/4

ss7ja [257]

Answer:

2t = 1 / 2

Step-by-step explanation:

2t = 1 / 2

t = 1 / ( 2 x 2 )

t = 1 / 4

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3 years ago

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Multiplying or dividing both sides by a negative number changes the direction of an inequality

omeli [17]

If you multiply or divide both sides by a negative number it changes the direction of the inequality sign

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4 years ago

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Complete the statement. If 11m = 6n, then m/n =?

maw [93]

M/n = 6/11 hope it helps you. Thanks

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1 year ago

Find the recursive quadratic formula of the sequence: 1, 3, 7, 13, 21

Anika [276]

The sequence

1, 3, 7, 13, 21, ...

has first-order differences

2, 4, 6, 8, ...

Let $a_n$ denote the original sequence, and $b_n$ the sequence of first-order differences. It's quite clear that

$b_n=2n$

for $n\ge1$ . By definition of first-order differences, we have

$b_n=a_{n+1}-a_n$

for $n\ge1$ , or

$a_{n+1}=a_n+2n$

By substitution, we have

$a_n=a_{n-1}+2(n-1)$

$\implies a_{n+1}=(a_{n-1}+2(n-1))+2n$

$\implies a_{n+1}=a_{n-1}+2(n+(n-1))$

$a_{n-1}=a_{n-2}+2(n-2)$

$\implies a_{n+1}=(a_{n-2}+2(n-2))+2(n+(n-1))$

$\implies a_{n+1}=a_{n-2}+2(n+(n-1)+(n-2))$

and so on, down to

$a_{n+1}=a_1+2(n+(n-1)+\cdots+2+1)$

You should know that

$1+2+\cdots+(n-1)+n=\dfrac{n(n+1)}2$

and we're given $a_1=1$ , so

$a_{n+1}=1+n(n+1)=n^2+n+1$

or

$a_n=(n-1)^2+(n-1)+1\implies\boxed{a_n=n^2-n+1}$

Alternatively, since we already know the sequence is supposed to be quadratic, we can look for coefficients $a,b,c$ such that

$a_n=an^2+bn+c$

We have

$a_1=a+b+c=1$

$a_2=4a+2b+c=3$

$a_3=9a+3b+c=7$

and we can solve this system for the 3 unknowns to find $a=1,b=-1,c=1$ .

4 0

4 years ago