What is the solution set for the open sentence with the given replacement set?

У=-3x+3 y = -9x + 15

julia-pushkina [17]

Answer:

(2, - 3 )

Step-by-step explanation:

Given the 2 equations

y = - 3x + 3 → (2)

y = - 9x + 15 → (2)

Substitute y = - 3x + 3 into (2)

- 3x + 3 = - 9x + 15 ( add 9x to both sides )

6x + 3 = 15 ( subtract 3 from both sides )

6x = 12 ( divide both sides by 6 )

x = 2

Substitute x = 2 into either of the 2 equations and solve for y

Substituting into (1)

y = - 3(2) + 3 = - 6 + 3 = - 3

solution is (2, - 3 )

8 0

3 years ago

Write the phrase as an expression. Then simplify the expression. The product of 8 and a number y multiplied by 9

Neporo4naja [7]

Answer:

8y x 9 ⇒ 72y

Step-by-step explanation:

5 0

3 years ago

100 points!! Brainliest if correct!!

Elena-2011 [213]

surface area (S) of a right rectangular solid is:

S = 2*L*W + 2*L*H + 2*W*H (equation 1)

where:

L = length

W = width

H = height

-----

you have:

L = 7

W = a

H = 4

-----

formula becomes:

S = 2*7*a + 2*7*4 + 2*a*4

simplify:

S = 14*a + 56 + 8*a

combine like terms:

S = 22*a + 56

-----

answer is:

S = 22*a + 56 (equation 2)

-----

to prove, substitute any value for a in equation 2:

let a = 15

S = 22*a + 56 (equation 2)

S = 22*15 + 56

S = 330 + 56

S = 386

-----

since a = 15, then W = 15 because W = a

go back to equation 1 and substitute 15 for W:

S = 2*L*W + 2*L*H + 2*W*H (equation 1)

where:

L = length

W = width

H = height

-----

you have:

L = 7

W = 15

H = 4

-----

equation 1 becomes:

S = 2*7*15 + 2*7*4 + 2*15*4

perform indicated operations:

S = 210 + 56 + 120

S = 386

-----

surface area is the same using both equations so:

equations are good.

formula for surface area of right rectangle in terms of a is:

S = 22*a + 56

-----

8 0

3 years ago

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Find the difference of 5 2/3 -4 5/9 A 3/4 B 1 1/9 C 1 1/2 D 8/9

sergey [27]

Answer: B- 1 1/9
Work:
5 2/3 - 4 5/9
1 2/3 - 5/9
1 6/9 - 5/9
= 1 1/9

5 0

3 years ago

Galena is solving the following system. 3x+2y+3z =5 7x+y +7z=-1 4x-4y-z=-3

babymother [125]

Answer:

She did not multiply equation 3 in step 2 by the correct value.

Step-by-step explanation:

Given:

$3x+2y+3z=5\\7x+y+7z=-1\\4x-4y-z=-3$

In order to solve this, we need to eliminate any one variable and then form a simultaneous equation with the remaining two variables. Then, we nee to solve the simultaneous equation.

Here, Galena is trying to eliminate the variable $z$ first.

Step 1: She multiplies equation (3) by 3 and adds it to equation (1)

Let us multiply equation (3) by 3

$(4x-4y-z=-3)\times 3 = (3\times 4x)-(3\times 4y)-(3\times z)=3\times -3\\(4x-4y-z=-3)\times 3 =12x-12y-3z=-9$

Now, adding this to equation 1 will cancel out z terms.

$12x-12y-3z+3x+2y+3z=-9+5\\(12x+3x)+(-12y+2y)+(3z-3z)=-4\\15x-10y+0=-4$

Now, she need to make one more equation in $x\ and \ y$ .

Step 2: She multiplies equation (3) by -7 and adds it to equation (2)

Multiplying equation (3) by -7 will give,

$(4x-4y-z=-3)\times -7 = (-7\times 4x)-(-7\times 4y)-(-7\times z)=-7\times -3\\(4x-4y-z=-3)\times 3 =-28x+28y+7z=21$

Now, adding this to equation 2 will not cancel out z terms.

$-28x+28y+7z+7x+y+7z=21-1\\(-28x+7x)+(28y+y)+(7z+7z)=20\\-21x+29y+14z=20$

So, she makes mistake in step 2 as the $z$ terms are not being cancelled.

6 0

3 years ago

Read 2 more answers