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2 years ago

-2x+y=9, x+2y=3 elimination

1 answer:

5 0

−2x+y=9
−2x+y+−y=9+−y
−2x=−y+9
−2x−2=−y+9−2
x=12y+−92

Now, x+2y=3
x+2y+−2y=3+−2y
x=−2y+3

Hoped I helped!

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Problem Solving

KATRIN_1 [288]

by unitary method the exact answer is correct (2,920 glasses).

given, glasses of water each day = 8

therefore, by unitary method :

glasses of water in 365 day = $8*365 = 2920$

hence the total glasses of water in 365 days = 2,920

learn more about unitary method here:

brainly.com/question/23423168

#SPJ9

3 0

1 year ago

I need some help with this

dalvyx [7]

$\pink{\underline{{\boxed{\bf{QUESTION: }}}}}$

-6(x+4) = _____

$\pink{\underline{{\boxed{\bf{OPTIONS:}}}}}$

6x - 4❌
-6x + 4❌
-6x - 24✔️
6x + 24❌

$\pink{\underline{{\boxed{\bf{ ANSWER: }}}}}$

-6(x+4) = -6x - 24

<h3>Hope It's helped! :)</h3>

4 0

2 years ago

I have to get this so I pass help plz

pshichka [43]

Answer:

$\boxed{\sf x=-2}$

$\boxed{\sf y=-4}$

Step-by-step explanation:

First, Let's solve for x in -2x+2y=-4:

$\sf -2x+2y=-4$

Subtract 2y from both sides:

$\sf -2x+2y-2y=-4-2y$

$\sf -2x=-4-2y$

Divide both sides by -2:

$\sf \cfrac{-2x}{-2}=-\cfrac{4}{-2}-\cfrac{2y}{-2}$

$\bold{ x=y+2}$

Now, we'll substitute x=y+2 to 3x+3y=-18:

$\sf 3x+3y=-18$

→ let x=2+y

$\sf 3\bold{(2+y)}+3y=-18$

Simplify:

$\sf 6+6y=-18$

Now, let's solve for y in 6+6y=-18

$\sf 6+6y=-18$

Subtract 6 from both sides:

$\sf 6+6y-6=-18-6$

$\sf 6y=-24$

Divide both sides by 6:

$\sf \cfrac{6y}{6}=\cfrac{-24}{6}$

$\bold{ y=-4}$

Now, substitute y=-4 into x=2+y:

$\sf x=2+y$

→ let y = -4

$\sf x=2+\bold{-4}$

$\bold{x=-2}$

Therefore, x=-2 and y=-4.

_____________________________________

5 0

1 year ago

Find the direction cosines and direction angles of the vector. (Give the direction angles correct to the nearest degree.) 5, 1,

Dahasolnce [82]

Answer:

The direction cosines are:

$\frac{5}{\sqrt{42} }$ , $\frac{1}{\sqrt{42} }$ and $\frac{4}{\sqrt{42} }$ with respect to the x, y and z axes respectively.

The direction angles are:

40°, 81° and 52° with respect to the x, y and z axes respectively.

Step-by-step explanation:

For a given vector a = ai + aj + ak, its direction cosines are the cosines of the angles which it makes with the x, y and z axes.

If a makes angles α, β, and γ (which are the direction angles) with the x, y and z axes respectively, then its direction cosines are: cos α, cos β and cos γ in the x, y and z axes respectively.

Where;

cos α = $\frac{a . i}{|a| . |i|}$ ---------------------(i)

cos β = $\frac{a.j}{|a||j|}$ ---------------------(ii)

cos γ = $\frac{a.k}{|a|.|k|}$ ----------------------(iii)

And from these we can get the direction angles as follows;

α = cos⁻¹ ( $\frac{a . i}{|a| . |i|}$ )

β = cos⁻¹ ( $\frac{a.j}{|a||j|}$ )

γ = cos⁻¹ ( $\frac{a.k}{|a|.|k|}$ )

Now to the question:

Let the given vector be

a = 5i + j + 4k

a . i = (5i + j + 4k) . (i)

a . i = 5 [a.i is just the x component of the vector]

a . j = 1 [the y component of the vector]

a . k = 4 [the z component of the vector]

Also

|a|. |i| = |a|. |j| = |a|. |k| = |a| [since |i| = |j| = |k| = 1]

|a| = $\sqrt{5^2 + 1^2 + 4^2}$

|a| = $\sqrt{25 + 1 + 16}$

|a| = $\sqrt{42}$

Now substitute these values into equations (i) - (iii) to get the direction cosines. i.e

cos α = $\frac{5}{\sqrt{42} }$

cos β = $\frac{1}{\sqrt{42} }$

cos γ = $\frac{4}{\sqrt{42} }$

From the value, now find the direction angles as follows;

α = cos⁻¹ ( $\frac{a . i}{|a| . |i|}$ )

α = cos⁻¹ ( $\frac{5}{\sqrt{42} }$ )

α = cos⁻¹ ( $\frac{5}{6.481}$ )

α = cos⁻¹ (0.7715)

α = 39.51

α = 40°

β = cos⁻¹ ( $\frac{a.j}{|a||j|}$ )

β = cos⁻¹ ( $\frac{1}{\sqrt{42} }$ )

β = cos⁻¹ ( $\frac{1}{6.481 }$ )

β = cos⁻¹ ( 0.1543 )

β = 81.12

β = 81°

γ = cos⁻¹ ( $\frac{a.k}{|a|.|k|}$ )

γ = cos⁻¹ ( $\frac{4}{\sqrt{42} }$ )

γ = cos⁻¹ ( $\frac{4}{6.481}$ )

γ = cos⁻¹ (0.6172)

γ = 51.89

γ = 52°

Conclusion:

The direction cosines are:

$\frac{5}{\sqrt{42} }$ , $\frac{1}{\sqrt{42} }$ and $\frac{4}{\sqrt{42} }$ with respect to the x, y and z axes respectively.

The direction angles are:

40°, 81° and 52° with respect to the x, y and z axes respectively.

3 0

2 years ago

The length of a rectangular garden is three feet less than twice it’s width. If the perimeter of the garden is 42 feet, what is

Masja [62]

Answer:

The length of a rectangular garden is: 13 feet

Step-by-step explanation:

You have 2 lengths that are 2x-3 feet, and 2 widths that are x.

2x-3 + 2x-3 +x +x =42 feet

4x -6 +2x -42 feet

6x -6 = 42 feet

6x = 48 feet

x = 8 feet (so, 2x-3 = 16-3 = 13 feet)

3 0

2 years ago