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3 years ago

Find the measure of angle A

Mathematics

1 answer:

mojhsa [17]3 years ago

7 0

Answer:

105+50=155 so 180 subtract 155 is 25

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What is the measure of DA? 15 90 105 165

seraphim [82]

Answer:

D. 165

Step-by-step explanation:

if A+n=180

75+90+n=180

165+n=180

n=180-165

n=15

A+n=180

A+15=180

A=180-15

A=165 (D)

3 0

3 years ago

Find a compact form for generating functions of the sequence 1, 8,27,... , k^3

pantera1 [17]

This sequence has generating function

$F(x)=\displaystyle\sum_{k\ge0}k^3x^k$

(if we include $k=0$ for a moment)

Recall that for $|x|$ , we have

$\displaystyle\frac1{1-x}=\sum_{k\ge0}x^k$

Take the derivative to get

$\displaystyle\frac1{(1-x)^2}=\sum_{k\ge0}kx^{k-1}=\frac1x\sum_{k\ge0}kx^k$

$\implies\dfrac x{(1-x)^2}=\displaystyle\sum_{k\ge0}kx^k$

Take the derivative again:

$\displaystyle\frac{(1-x)^2+2x(1-x)}{(1-x)^4}=\sum_{k\ge0}k^2x^{k-1}=\frac1x\sum_{k\ge0}k^2x^k$

$\implies\displaystyle\frac{x+x^2}{(1-x)^3}=\sum_{k\ge0}k^2x^k$

Take the derivative one more time:

$\displaystyle\frac{(1+2x)(1-x)^3+3(x+x^2)(1-x)^2}{(1-x)^6}=\sum_{k\ge0}k^3x^{k-1}=\frac1x\sum_{k\ge0}k^3x^k$

$\implies\displaystyle\frac{x+4x^3+x^3}{(1-x)^4}=\sum_{k\ge0}k^3x^k$

so we have

$\boxed{F(x)=\dfrac{x+4x^3+x^3}{(1-x)^4}}$

5 0

4 years ago

Suppose that w and t vary inversely and that t = 5/12

Svetlanka [38]

Answer:

Option B. t=5/3w ;1/3

Step-by-step explanation:

We are told that $w$ varies Inversely with $t$ thus generally speaking $w$ ∝ $\frac{1}{t}$ since they are inverted, <u>otherwise</u> if they were proportionally varied then $w$ ∝ $t$ . This means that there is a constant value ( $a$ ) for which $w$ is inversely proportional to $t$ and can be mathematically expressed as:

$w=\frac{a}{t}$ Eqn. (1)

Now since we are given the values of $w=4$ and $t=\frac{5}{12}$ , we can plug them in Eqn. (1) and find our constant of proportionality $a$ as follow:

$w=\frac{a}{t}\\ \\a=wt\\\\a=(4)(\frac{5}{12} )\\\\a=\frac{5}{3}$

Now that we have our constant we can find the new $t$ value for the second value of $w=5$ as follow:

$w=\frac{a}{t} \\\\t=\frac{a}{w}\\ \\t=\frac{\frac{5}{3} }{5}\\\\t=\frac{5}{15}\\ \\t=\frac{1}{3}\\$

Therefore based on the options give, we can see that Option B. is correct since

$t=\frac{5}{3w}$ and for $w=5$ , then $t=\frac{1}{3}$

8 0

3 years ago

X^2-3x-28=0 what are the roots

Oksi-84 [34.3K]

Answer:

$\large\boxed{x=-4\ \vee\ x=7}$

Step-by-step explanation:

$x^2-3x-28=0\\\\x^2+4x-7x-28=0\\\\x(x+4)-7(x+4)=0\\\\(x+4)(x-7)=0\iff x+4=0\ \vee\ x-7=0\\\\x+4=0\qquad\text{subtract 4 from both sides}\\x=-4\\\\x-7=0\qquad\text{add 7 to both sides}\\x=7$