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3 years ago

10x-3×=-18 -7×-8y=11A.(-7,-10)B.(-4,5)C.(3,-4)D.(2,-1)

Mathematics

1 answer:

Ivahew [28]3 years ago

7 0

Answer:

Step-by-step explanation:

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Two -thirds of the children in the fourth grade class are girls. If there are 18 girls, what is the total of children in the cla

Yanka [14]

There are 27 children in the class.

18 divided by two equals 9
9 times 3 is 27

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2 years ago

Which set of values could be the sides lengths of a 30-60-90 triangle

Maslowich

Hello,

Let's assume a the hypotenuse

b/a=sin 30°==>b=a/2

c/a=cos 30°==>c=√3 / 2 *a

(√3/2 a, a/2,a) are the sides of the triangle.

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2 years ago

Joey and Nolan are each solving the equation 13x - 42 = 18 - 7x.

poizon [28]

Answer:

First step=13x+7x=18+42

Step-by-step explanation:

13x-42=18-7x

First step

It is to collect like terms of the equation

13x+7x=18+42

20x=60

x=60/20

x=3

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3 years ago

A street light is at the top of a 25 ft pole. A 4 ft tall girl walks along a straight path away from the pole with a speed of 6

Burka [1]

Answer:

Tip of the shadow of the girl is moving with a rate of 7.14 feet per sec.

Step-by-step explanation:

Given : In the figure attached, Length of girl EC = 4 ft

Length of street light AB = 25 ft

Girl is moving away from the light with a speed = 6 ft per sec.

To Find : Rate ( $\frac{dw}{dt}$ ) of the tip (D) of the girl's shadow (BD) moving away from th

light.

Solution : Let the distance of the girl from the street light is = x feet

Length of the shadow CD is = y feet

Therefore, $\frac{dx}{dt}=6$ feet per sec. [Given]

In the figure attached, ΔAFE and ΔADE are similar.

By the property of similar triangles,

$\frac{x}{21}=\frac{x+y}{25}$

25x = 21(x + y)

25x = 21x + 21y

25x - 21x = 21y

4x = 21y

y = $\frac{4x}{21}$

Now we take the derivative on both the sides,

$\frac{dy}{dt}=\frac{4}{21}\times \frac{dx}{dt}$

= $\frac{4}{21}\times 6$

= $\frac{8}{7}$

≈ 1.14 ft per sec.

Since w = x + y

Therefore, $\frac{dw}{dt}= \frac{dx}{dt}+\frac{dy}{dt}$

$\frac{dw}{dt}=6+1.14$

= 7.14 ft per sec.

Therefore, tip of the shadow of the girl is moving with a rate of 7.14 feet per sec.

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3 years ago

Express x^2y^2+x^2+y^2+1

Hitman42 [59]

Answer:

( y^2 +1) ( x^2+1)

Step-by-step explanation:

Step 1 ) Factor out x^2 from the expression

x^2 (y^2+1)+y^2+1

Step 2) Factor out y^2 from the expression

(y^2+1) (x^2+1)

Solution is ( y^2 +1) ( x^2+1)

5 0

2 years ago