What is -9 to the second power

Mathematics

2 answers:

OLEGan [10]3 years ago

4 0

-9 to the second power will most likely be 81. A negative x a negative equals a positive. Hope this helped.

Kamila [148]3 years ago

3 0

Answer:

$-9^{2} = 81$

Explanation:

Since you have to square -9 twice, you get 81 because $-9*-9=81$ .

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During second period,Emma completed a grammar worksheet.Of the 60 questions Emma got 90% right how many questions did Emma get r

Alona [7]

She got 54 questions rights.
Explanation: Multiply 60 by .9. The decimal is the percentage you need to find, example (30*.3) .3 is thirty percent.

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3 years ago

The half-life of a certain tranquilizer in the bloodstream is 22 hours. How long will it take for the drug to decay to 90% of

nasty-shy [4]

Answer:

It will take approximately 3.34 hours for the drug to decay to 90% of the original dosage

Step-by-step explanation:

As suggested, we use the formula for exponential decay:

$A(t)=A_0\,e^{-k\,t}$

From the given information, the half life of the drug in blood id 22 hours, so that means that it takes that number of hours to go from the initial value $A_0$ , to a final value equal to $A_0/2$ . Using this information we can find the decay rate "k" by solving for this parameter in the formula, and using the natural log function to bring the exponent down:

$A(t)=A_0\,e^{-k\,t}\\\frac{A_0}{2} =A_0\,e^{-k\,*22}\\\frac{A_0}{A_0*2} =e^{-k\,*22}\\\frac{1}{2} =e^{-k\,*22}\\ln(\frac{1}{2})=-k\,*22\\ k=-\frac{ln(\frac{1}{2})}{22} \\k=0.0315$

Now we use this value for the decay rate "k" to calculate how long it would take to decay to 90% of the original dose;

$A(t)=A_0\,e^{-0.0315\,t}\\0.9*A_0} =A_0\,e^{-0.0315\,t}\\\frac{0.9*A_0}{A_0} =e^{-0.0315\,t}\\0.9 =e^{-0.0315\,t}\\ln(0.9)=-0.0315\,t\\ t=-\frac{ln(0.9)}{0.0315} \\t=3.3447\,hours$

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3 years ago

Whats is y=1/3x+2 This is for math

marusya05 [52]

Answer:

an equation of a line

Step-by-step explanation:

This is an equation of a line. Lets walk through it.

y=1/3x+2

This is to find out what the Y coordinate would be when X is plugged in. So, if x was 6, you would take 1/3 of 6 to get 2, and add 2. The y intercept would be 4, since y=1/3(6)+2, y=2+2, y=4

Y=1/3x+2

This is what the slope is. If the slope is negative (ie. -3/4) the greater the x intercept the lower the y will be. (so if I had x=4 for a slope of -3/4, that would be y=-3/4(4)+2, y=-3+2, y=-1) But if the slope is positive (ie. 1/3) the greater the x value the greater the y value as well. (see graph attached below for positive)

Y=1/3x+2

This is the Y intercept. (This is NOT the y coordinate. This is only the coordinate of y if x=0) This number tells you where the Y intercept is. If it adds, the y intercept is positive. If it subtracts, the y intercept is negative.

Sorry if these explainations dont make sense. But, here is the graph for y=1/3x+2