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Alja [10]
3 years ago
11

Solve the system of linear equations using linear combination.

Mathematics
1 answer:
snow_lady [41]3 years ago
8 0

Answer:

a = 1, b = 7

Step-by-step explanation:

Given the 2 equations

3a + 6b = 45 → (1)

2a - 2b = - 12 → (2)

Multiply (2) by 3 and add to (1) to eliminate the term in b

6a - 6b = - 36 → (3)

Add (1) and (3) term by term

(3a + 6a) + (6b - 6b) = (45 - 36)

9a = 9 ( divide both sides by 9 )

a = 1

Substitute a = 1 in either (1) or (2) and solve for b

(1) → 3 + 6b = 45 ( subtract 3 from both sides )

6b = 42 ( divide both sides by 6 )

b = 7

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5 ≤ x ≤ 10             5 ≤ y ≥ -1

Step-by-step explanation:

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3 years ago
Please help asap!!! i dont understand it
pshichka [43]

Answer:

a

Step-by-step explanation:

A perpendicular bisector, intersects a line at its mid point and is perpendicular to it.

Calculate slope m using the slope formula

m = \frac{y_{2}-y_{1}  }{x_{2}-x_{1}  }

with (x₁, y₁ ) = (- 7, 1) and (x₂, y₂ ) = (9, 13)

m = \frac{13-1}{9-(-7)} = \frac{12}{9+7} = \frac{12}{16} = \frac{3}{4}

Given a line with slope m then the slope of a line perpendicular to it is

m_{perpendicular} = - \frac{1}{m} = - \frac{1}{\frac{3}{4} } = - \frac{4}{3} ←  slope of perpendicular bisector

Given endpoints (x₁, y₁ ) and (x₂, y₂ ) then the midpoint is

(\frac{x_{1}+x_{2}  }{2}, \frac{y_{1}+y_{2}  }{2} )

using (x₁, y₁ ) = (- 7, 1) and (x₂, y₂ ) = (9, 13) , then

midpoint = ( \frac{-7+9}{2}, \frac{1+13}{2} ) = ( \frac{2}{2}, \frac{14}{2} ) = (1, 7 )

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Here m = - \frac{4}{3} , then

y = - \frac{4}{3} x + c ← is the partial equation

To find c substitute the midpoint (1, 7) into the partial equation

7 = - \frac{4}{3} + c ⇒ c = \frac{21}{3} + \frac{4}{3} = \frac{25}{3}

y = - \frac{4}{3} x + \frac{25}{3} ← equation of perpendicular bisector

7 0
3 years ago
A circular region has a population of about 15,500 people and a population density of about 775 people per square kilometer. Fin
Reil [10]

Answer:

2.5 km

Step-by-step explanation:

First, find the area of the region:

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  • A population density of about 775 people per square kilometer.

So, there are 15,500 :775=20 square kilometers.

Now, let x kilometers be the radius of the circular region, then

A_{\text{circilar region}}=\pi r^2\\ \\20=\pi r^2\\ \\r^2=\dfrac{20}{\pi}\approx 6.366198\\ \\r=\sqrt{3.366198}\approx 2.523

To the nearest tenth this is 2.5 km.

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I hope this helps you



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According to Piaget, adolescents have entered the final stage of cognitive development. The _____ stage enables adolescents to t
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Answer:

The formal operational stage.

Step-by-step explanation:

According to Piaget, adolescents have entered the final stage of cognitive development. The <u>formal operational</u> stage enables adolescents to think logically about tangible and abstract ideas.

As per Piaget: there are four stages of cognitive development.

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The Sensorimeter Stage: It is a stage of age between 0-2 years, wherein kids start using senses of touch, watching and listening to understand and feel the world around.

The Preoperational Stage: It is a stage of age between 2-7 years, wherein kids develop language and start talking about things.

The concrete operational Stage: It is a stage of age between 7-11 years, wherein kids learn logical concrete rule and start having conversation.

The formal operational stage: It is the stage of age group of 11 and above. At this stage children start thinking logically about tangible and abstract ideas.

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