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3 years ago

PLEASE HELP

Mathematics

1 answer:

stira [4]3 years ago

5 0

Answer:

The values of x and y are x = 3 and y = 11

Step-by-step explanation:

The isosceles triangle has two equal sides in length, and its base angles are equal in measures

In ΔJKL

∵ ΔJKL is an isosceles triangle with vertex K

→ That means the equal sides are JK and KL

∴ JK = KL

∵ JK = 8x and KL = 13x - 15

→ Equate them

∴ 13x - 15 = 8x

→ Add 15 to both sides

∵ 13x - 15 + 15 = 8x + 15

∴ 13x = 8x + 15

→ Subtract 8x from both sides

∵ 13x - 8x = 8x - 8x + 15

∴ 5x = 15

→ Divide both sides by 5 to find x

∴ x = 3

∵ K is the vertex of the ΔJKL

∴ ∠KJL and ∠KLJ are the base angles

∵ The base angles are equal in measures

∴ m∠KJL = m∠KLJ

∵ m∠KJL = 5y - 3

∴ m∠KLJ = 5y - 3

∵ The sum of the measures of the angles of a Δ is 180°

∴ m∠KJL + m∠KLJ + m∠JKL = 180°

∵ m∠JKL = 76°

→ Substitute the measures of the 3 angles in the equation

∴ 5y - 3 + 5y - 3 + 76 = 180

→ Add the like terms on the left side

∵ (5y + 5y) + (76 - 3 - 3) = 180

∴10y + 70 =180

→ Subtract 70 from both sides

∵ 10y + 70 - 70 = 180 - 70

∴ 10y = 110

→ Divide both sides by 10 to find y

∴ y = 11

∴ The values of x and y are x = 3 and y = 11

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Step-by-step explanation:

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3 years ago

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Evaluate the function below for x = 2.<br>f (x) = 4x^3 - x^2 - 5x+7<br>

nexus9112 [7]

Answer: $f(2)=25$

Step-by-step explanation:

You know that the given function is:

$f(x)=4x^3-x^2-5x+7$

You know that you must evaluate this function for $x=2$ .

Then, to evaluate the function for $x=2$ , you need to substitute this value into the given function and simplify it.

Therefore, you get:

$f(x)=4x^3-x^2-5x+7\\f(2)=4(2)^3-(2)^2-5(2)+7\\f(2)=4(8)-(4)-10+7\\f(2)=32-4-10+7\\f(2)=25$

So, the answer is: $f(2)=25$

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3 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. $a(t)=\frac{dv}{dt}$

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.

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4 years ago

Explain how using basic facts can help you find 10×20×30×40 mentally?

Katena32 [7]

So all you have to do is take the first numbers of each multiple and multiply them.
1 x 2 x 3 x 4 = 24
Now you just add the 4 zeros to your answer.
240,000

Our answer even checks!
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Good Luck! :)

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4 years ago

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