Question

8)

Solve the system 2x + 5y = 7 and 3x + 4y = 6 by elimination. Which procedure produces opposite terms to eliminate x? Include
proper justification.
Multiply the first equation by 3 and multiply the second equation by -2.
This is justified by the commutative property of addition
Multiply the first equation by 4 and multiply the second equation by -5.
This is justified by the commutative property of addition.
Multiply the first equation by 3 and multiply the second equation by -2.
This is justified by the multiplication property of equality.
Multiply the first equation by 4 and multiply the second equation by -5.
This is justified by the multiplication property of equality

Answer 1

i did the assignment i hope this helps! :)

1.) a & b

2.) a

3.) c

Explanation:

Consider these chemical equations.

N2(g) + 3H2(g) → 2NH3(g)

C(s) + 2H2(g) → CH4(g)

4H2(g) + 2C(s) + N2(g) → 2HCN(g) + 3H2(g)

Which equation(s) do you need to reverse in order to calculate the overall equation for the formation of HCN and H2 from NH3 and CH4? Check all that apply.

N2(g) + 3H2(g) 2NH3(g)

C(s) + 2H2(g) CH4(g)

4H2(g) + 2C(s) + N2(g) 2HCN(g) + 3H2(g)

What must you do before adding the equations?

multiply the second equation by 2

multiply the first equation by 1/3

multiply the third equation by 1/2

What is the overall reaction equation?

the last option!!!!

NH3(g) + CH4(g) 3H2(g) + HCN(g)

Answer 2

Multiply the first equation by 3 and multiply the second equation by -2.

This is justified by the multiplication property of equality

Explanation:

we have

`2x+5y=7` ----> first equation

`3x+4y=6` ----> second equation

step 1

Multiple the first equation by 3 both sides

`3(2x+5y)=3(7)` -----> by multiplication property of equality

`6x+15y=21` ----> new first equation

step 2

Multiple the second equation by -2 both sides

`-2(3x+4y)=-2(6)` -----> by multiplication property of equality

`-6x-8y=-12` ----> new second equation

step 3

Solve the system of equations by elimination

Adds new first equation and new second equation

`6x+15y=21\\-6x-8y=-12\\-------\\15y-8y=21-12\\7y=9\\y=(9)/(7)`

Find the value of x

substitute the value of y in any equation and solve for x

`6x+15y=21`

`6x+15((9)/(7))=21`

`6x=21-(135)/(7)`

`6x=(12)/(7)`

`x=(2)/(7)`

The solution is the point
`((2)/(7),(9)/(7))`

therefore

Multiply the first equation by 3 and multiply the second equation by -2.

This is justified by the multiplication property of equality