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3 years ago

Y=-3x+5 5x - 4y= -3 solvining systems of equations by substitution

1 answer:

4 0

$\left\{\begin{array}{ccc}y=-3x+5\\5x-4y=-3\end{array}\right\\\\\\substitute\\\\5x-4(-3x+5)=-3\\5x+12x-20=-3\\17x-20=-3\\17x=-3+20\\17x=17\ \ \ \ /:17\\x=1\\\\y=-3\cdot1+5=-3+5=2\\\\ \left\{\begin{array}{ccc}x=1\\y=2\end{array}\right$

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The temperature, H, in degrees Celsius, of a cup of coffee placed on the kitchen counter is given by H = f(t), where t is in min

Deffense [45]

Answer:

f'(t) is negative

The unit is degC/min

At 35 minutes after the coffee was put on the counter, its temperature is 68 and will decrease by about 0.75 in the next 30 seconds.

Step-by-step explanation:

From the question we are told we are told that

The equation for the temperature of a cup of coffee place on a counter is

$H= f(t)$

Here t is the time in minutes the coffee was put on the counter

Generally f(t)' is the derivative of f(t) at it represents the change of the temperature of the cup of coffee with respect to time

Generally for the coffee placed on the counter after a couple of minutes the temperature will decrease hence f(t)' is negative

Generally the unit of the temperature is in degrees Celsius while that of time is in minutes

So the change in temperature with time f(35)' will be in degrees Celsius/minutes (i.e degC/min)

From the question we are told that

$|f(35)'| = 1.5$

i.e the rate of change of temperature after 35 minutes is 1.5

and

$|f(35)| = 68$

i.e the temperature of the cup of coffee after 35 minutes is 67 degC

Now after another t= 30 seconds = $\frac{30}{60}= 0.5 \ minutes$ the rate of change of the temperature of the cup of coffee is

$R = |f(35)'| * t$

=> $R = 1.5 * 0.5$

=> $R = 0.75$

At 35 minutes after the coffee was put on the counter, its temperature is 68 and will decrease by about 0.75 in the next 30 seconds.

5 0

3 years ago

The quotient of a number and 4 is at most 5

gladu [14]

N/4 less than or equal to 5

5 0

3 years ago

Which function has zeros at x = -2 and x = 5?

riadik2000 [5.3K]

Answer:

f(x)=x²-3x-10

Step-by-step explanation:

\begin{gathered}f(x) = x {}^{2} - 3x - 10 \\ to \: find \: x \: intercept \:o r \: zero \: substitute \: f(x) = 0\: \\ 0 = x {}^{2} - 3x - 10 \\ x {}^{2} - 3x - 10 = 0 \\ x {}^{2} + 2x - 5x - 10 = 0 \\ x(x + 2) - 5x - 10 = 0 \\ x(x + 2) - 5(x + 2) = 0 \\ (x + 2).(x - 5) = 0 \\ x + 2 = 0 \\ x - 5 = 0 \\ x = - 2 \\ x = 5\end{gathered}

f(x)=x

−3x−10

tofindxinterceptorzerosubstitutef(x)=0

0=x

−3x−10

−3x−10=0

+2x−5x−10=0

x(x+2)−5x−10=0

x(x+2)−5(x+2)=0

(x+2).(x−5)=0

x+2=0

x−5=0

x=−2

x=5

therefore the zeros of the equation are x₁=-2,x₂=5

3 0

1 year ago

A team of 17 softball players need to choose three players to refill the water cooler. How many different ways are there to sele

KATRIN_1 [288]

<h3>Answer: 680 different combinations</h3>

=======================================================

Explanation:

If order mattered, then we'd have 17*16*15 = 4080 different permutations. Notice how I started with 17 and counted down 1 at a a time until I had 3 slots to fill. We count down by 1 because each time we pick someone, we can't pick them again.

So we have 4080 different ways to pick 3 people if order mattered. But again order doesn't matter. All that counts is the group itself rather than the individual or how they rank. There are 3*2*1 = 6 ways to order any group of three people, which means there are 4080/6 = 680 different combinations possible.

An alternative is to use the nCr formula with n = 17 and r = 3. That formula is

$_n C _r = \frac{n!}{r!*(n-r)!}$

where the exclamation marks indicate factorials

5 0

3 years ago

Which of the following points lies in the l and ll quadrants.

meriva

Answer:

Quadrant I: (1,1), (4,3)

Quadrant II: (-2, 3), (-1, 1)

Step-by-step explanation:

Quadrant I points have positive x and y values. Quandrant II points have negative x values and positive y values.

5 0

3 years ago