Ask question

Ask question

All categories

4 years ago

7

Find the value of r 4(x-3) -r +2x =5(3x-7) -9x Please help me

1 answer:

lbvjy [14]4 years ago

6 0

$4(x-3)-r+2x=5(3x-7)-9x\ \ \ |\text{use distributive property}\\\\(4)(x)+(4)(-3)-r+2x=(5)(3x)+(5)(-7)-9x\\\\4x-12-r+2x=15x-35-9x\\\\(4x+2x)-12-r=(15x-9x)-35\\\\6x-12-r=6x-35\ \ \ \ |-6x\\\\-12-r=-35\ \ \ \ |+12\\\\-r=-23\to\boxed{r=23}$

You might be interested in

X²-5÷x-2<br>quiero la respuesta

Mashutka [201]

Evaluate the power,subtract the numbers then write all the numerator above the common denominator.

6 0

3 years ago

Can someone please answer this (please don’t send a tinyurl link)

sweet [91]

A. 35% decrease yearly
B. 267.75
C. How much the computer is worth after 4 years

7 0

3 years ago

constitutional amendment that has significantly changed the structure of congress as written in the original constitution

dezoksy [38]

This isn’t the correct way because

5 0

2 years ago

Initially 100 milligrams of a radioactive substance was present. After 6 hours the mass had decreased by 3%. If the rate of deca

Hitman42 [59]

Answer:

The half-life of the radioactive substance is 135.9 hours.

Step-by-step explanation:

The rate of decay is proportional to the amount of the substance present at time t

This means that the amount of the substance can be modeled by the following differential equation:

$\frac{dQ}{dt} = -rt$

Which has the following solution:

$Q(t) = Q(0)e^{-rt}$

In which Q(t) is the amount after t hours, Q(0) is the initial amount and r is the decay rate.

After 6 hours the mass had decreased by 3%.

This means that $Q(6) = (1-0.03)Q(0) = 0.97Q(0)$ . We use this to find r.

$Q(t) = Q(0)e^{-rt}$

$0.97Q(0) = Q(0)e^{-6r}$

$e^{-6r} = 0.97$

$\ln{e^{-6r}} = \ln{0.97}$

$-6r = \ln{0.97}$

$r = -\frac{\ln{0.97}}{6}$

$r = 0.0051$

So

$Q(t) = Q(0)e^{-0.0051t}$

Determine the half-life of the radioactive substance.

This is t for which Q(t) = 0.5Q(0). So

$Q(t) = Q(0)e^{-0.0051t}$

$0.5Q(0) = Q(0)e^{-0.0051t}$

$e^{-0.0051t} = 0.5$

$\ln{e^{-0.0051t}} = \ln{0.5}$

$-0.0051t = \ln{0.5}$

$t = -\frac{\ln{0.5}}{0.0051}$

$t = 135.9$

The half-life of the radioactive substance is 135.9 hours.

6 0

3 years ago

Hey anyone know this ?

Sergeu [11.5K]

Answer:

It's an equilateral triangle so the measure of each angle here=60 degrees

s..4x degree=15*4

hence, the value of X=15

<h2>Have a good day Ahead:)</h2>

6 0

3 years ago