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3 years ago

Find the value of the expression 2x²-5x+6

Mathematics

1 answer:

Vedmedyk [2.9K]3 years ago

7 0

33x I think sorry if I am wrong

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Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te

Aleonysh [2.5K]

Answer:

t=5.18 minute

Step-by-step explanation:

Using Newton's law of cooling

$\frac{dT}{dt}=-k(T-T_{s})$

T is temperature of a cup of coffee at any time t $T_{s}$ , is the temperature of the surrounding and k is a constant of proportionality in this negative because temperature is decreasing.

$T(0)=190\\T(1)=170\\T_{s}=66$

$\frac{dT}{dt}=-k(T-T_{s})\\\frac{dT}{(T-T_{s})}=-k*dt\\\int\limits {\frac{1}{T-T_{s} } } \, dT=-\int\limits {k} \, dt\\ln(T-T_{s})=k*t+C\\e*ln(T-T_{s})=e^{k*t+C} \\T-T_{s}=e^{k*t}*e^{C}\\e^{C}=C\\T-T_{s}=e^{k*t}*C\\T=T_{s}+e^{k*t}*C$

To find constant knowing the time and the temperature the first step of the change of energy in cup of coffee

$T=T_{s} +e^{-k*t}*C\\ C=190-66=124\\170=66+124*e^{-k*2}\\ 170-66=124*e^{-k*2}\\ln(\frac{104}{124})=ln*e^{-k*2}\\-0.175=-k*2\\k=0.08794$

Now using the constant of decreasing can find the time to be a 145 temperature the cup of coffee

$145=66+124*e^{-k*t} \\145-66=124*^{-0.087*t}$

$ln(0.637)=ln*e(-0.087*t)\\-0.45=-0.087*t\\t=5.18minutes$

4 0

3 years ago

Please help! I will mark brainliest!! :)

Mekhanik [1.2K]

Answer:

The possibility it is red is 0%

Step-by-step explanation:

Because there are no red marbles

6 0

3 years ago

Find sin 2x,cos2x and tan2x,if tanx=-(3)/(4)and x terminates in quadrant IV

Montano1993 [528]

Answer:PLEASE HELP ME

Step-by-step explanation:

here can you guys please help me with this question.

I have been asking help from so many people but no one is nice enough to give it so im hoping that anyone over here can help me. this is the problem

Carl is standing at the base of a zip line which is 400 ft away from the base of the building that is connected to the top of a building. Standing 5.5 ft tall, he looks up to the top of the building at an angle of elevation of 25 degrees. A weight is released and travels down the zip line to his feet. How far did the weight travel? Round to nearest 10th of a foot and do not use units in your answer.

Please show work

7 0

3 years ago

17 The table shows some information about the dress sizes of 25 women.

eimsori [14]

Answer:

8.5 or 8½

Step-by-step explanation:

Arranged numbers in ascending order

2, 6, 8, 8, 9, 10, 12, 14

Median = middle number i. e 8 and 9

Therefore median = 8 + 9 divided by 2

= 17 divided 2

= 8.5

Answers = 8.5 or 8½

6 0

3 years ago

Solve the equation <br>8-2x=-8x+14

Marina86 [1]

8 - 2x = -8x + 14 <em>subtract 8 from both sides</em>

-2x = -8x + 6 <em>add 8x to both sides</em>

6x = 6 <em>divide both sides by 6</em>

4 0

3 years ago

Read 2 more answers