Y=4x+1 in standard form

we do not know how much the price of a commodity is, but it has been reduced by 10% and now costs 20€. What was the starting pri

MrRissso [65]

I got 22 because if u do 20 multiplied by 10% that gives u 2 which u then add onto the 20 to get the starting price. 10% of 22 is 2 and then 22-2 = 20 (if u we’re doing it from the starting price)

4 0

2 years ago

A rock thrown vertically upward from the surface of the moon at a velocity of 36m/sec reaches a height of s = 36t - 0.8 t^2 met

Verdich [7]

Answer:

a. The rock's velocity is $v(t)=36-1.6t \:{(m/s)}$ and the acceleration is $a(t)=-1.6 \:{(m/s^2)}$

b. It takes 22.5 seconds to reach the highest point.

c. The rock goes up to 405 m.

d. It reach half its maximum height when time is 6.59 s or 38.41 s.

e. The rock is aloft for 45 seconds.

Step-by-step explanation:

Velocity is defined as the rate of change of position or the rate of displacement. $v(t)=\frac{ds}{dt}$
Acceleration is defined as the rate of change of velocity. $a(t)=\frac{dv}{dt}$

a.

The rock's velocity is the derivative of the height function $s(t) = 36t - 0.8 t^2$

$v(t)=\frac{d}{dt}(36t - 0.8 t^2) \\\\\mathrm{Apply\:the\:Sum/Difference\:Rule}:\quad \left(f\pm g\right)'=f\:'\pm g'\\\\v(t)=\frac{d}{dt}\left(36t\right)-\frac{d}{dt}\left(0.8t^2\right)\\\\v(t)=36-1.6t$

The rock's acceleration is the derivative of the velocity function $v(t)=36-1.6t$

$a(t)=\frac{d}{dt}(36-1.6t)\\\\a(t)=-1.6$

b. The rock will reach its highest point when the velocity becomes zero.

$v(t)=36-1.6t=0\\36\cdot \:10-1.6t\cdot \:10=0\cdot \:10\\360-16t=0\\360-16t-360=0-360\\-16t=-360\\t=\frac{45}{2}=22.5$

It takes 22.5 seconds to reach the highest point.

c. The rock reach its highest point when t = 22.5 s

Thus

$s(22.5) = 36(22.5) - 0.8 (22.5)^2\\s(22.5) =405$

So the rock goes up to 405 m.

d. The maximum height is 405 m. So the half of its maximum height = $\frac{405}{2} =202.5 \:m$

To find the time it reach half its maximum height, we need to solve

$36t - 0.8 t^2=202.5\\36t\cdot \:10-0.8t^2\cdot \:10=202.5\cdot \:10\\360t-8t^2=2025\\360t-8t^2-2025=2025-2025\\-8t^2+360t-2025=0$

For a quadratic equation of the form $ax^2+bx+c=0$ the solutions are

$x_{1,\:2}=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$\mathrm{For\:}\quad a=-8,\:b=360,\:c=-2025:\\\\t=\frac{-360+\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2-\sqrt{2}\right)}{4}\approx 6.59\\\\t=\frac{-360-\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2+\sqrt{2}\right)}{4}\approx 38.41$

It reach half its maximum height when time is 6.59 s or 38.41 s.

e. It is aloft until s(t) = 0 again

$36t - 0.8 t^2=0\\\\\mathrm{Factor\:}36t-0.8t^2\rightarrow -t\left(0.8t-36\right)\\\\\mathrm{The\:solutions\:to\:the\:quadratic\:equation\:are:}\\\\t=0,\:t=45$

The rock is aloft for 45 seconds.

5 0

3 years ago

Aiden and Haisem are going to eat the same amount of hamburgers and fries, but from different restaurants. Aiden goes to Burger

Paha777 [63]

Answer:

the burgers be 3 and fries be 2

Step-by-step explanation:

The computation is shown below:

Let us assume burgers be x

And, the fries be y

Now according to the questiojn

1.25x + 0.50y = $4.75

1.50x + 0.99y = $6.48

Now multiply by 1.2 in the first equation

1.50x + 0.6y = $5.70

1.50x + 0.99y = $6.48

-0.39y = -0.78

y = 2

Now put the value of y in any of the above equation

1.25x + 0.50(2) = $4.75

x = 3

Hence, the burgers be 3 and fries be 2

6 0

2 years ago

49x2 - 81 is an example of the difference of two

Shkiper50 [21]

Answer:

(4x + 3)(4x - 3) represents the factorization of a polynomial that was the difference of two squares as it is written as product of sum and difference of two numbers.

Step-by-step explanation:

Formulas are used to factorize the polynomials.

In the given question, we can see a difference of squares

the difference of squares can be factorized using the formula

$a^2-b^2 = (a+b)(a-b)$

Here a^2 and b^2 are squares and factorized as sum and difference of numbers.

So in the given options,

(4x + 3)(4x - 3) represents the factorization of a polynomial that was the difference of two squares as it is written as product of sum and difference of two numbers.

7 0

2 years ago

In a rectangle KLMN, the diagonals KM and LN intersect at O.

elena-s [515]

Answer:

8y°±94°⊂⊂100°

Step-by-step explanation:

7 0

3 years ago