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2 years ago

Please help me solve 3x + 4y =15 and 3x - y = 30 it is for Algebra I

Mathematics

2 answers:

Makovka662 [10]2 years ago

7 0

Answer:

Step-by-step explanation:

Given the simultaneous equation

3x+4y=15. Equation 1

3x-y=30. Equation 2

Using elimination method

Sutract equation 2 from 1

Then, will have

3x-3x+4y--y=15-50. -×-=+

4y+y=-15

5y=-15

Divide Both sides by 5

y=-15/5

y=-3

From equation 2

3x-y=30

3x--3=30

3x+3=30

3x=30-3

3x=27

Divide both side by 3

x=27/3

x=9

Then, x=9 and y=-3

Colt1911 [192]2 years ago

7 0

Answer:

x=7 y=-9

Step-by-step explanation:

Use a system of equations to solve.

3x-y=30 changes to y=-30+3x

This can then be substituted into the other equation.

3x+4(-30+3x)=15

solve for x

X=7

Now use 7 in the other equation.

y=-30+x(7)

y=-9

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Simplify: cos2x-cos4 all over sin2x + sin 4x

GrogVix [38]

Answer:

$\frac{\cos\left(2x\right)-\cos\left(4x\right)}{\sin\left(2x\right)+\sin\left(4x\right)}=\tan\left(x\right)$

Step-by-step explanation:

$\frac{\cos\left(2x\right)-\cos\left(4x\right)}{\sin\left(2x\right)+\sin\left(4x\right)}$

Apply formula:

$\cos\left(A\right)-\cos\left(B\right)=-2\cdot\sin\left(\frac{A+B}{2}\right)\cdot\sin\left(\frac{A-B}{2}\right)$ and

$\sin\left(A\right)+\sin\left(B\right)=2\cdot\sin\left(\frac{A+B}{2}\right)\cdot\sin\left(\frac{A-B}{2}\right)$

We get:

$=\frac{-2\cdot\sin\left(\frac{2x+4x}{2}\right)\cdot\sin\left(\frac{2x-4x}{2}\right)}{2\cdot\sin\left(\frac{2x+4x}{2}\right)\cdot\cos\left(\frac{2x-4x}{2}\right)}$

$=\frac{-\sin\left(\frac{2x-4x}{2}\right)}{\cos\left(\frac{2x-4x}{2}\right)}$

$=\frac{-\sin\left(\frac{-2x}{2}\right)}{\cos\left(\frac{-2x}{2}\right)}$

$=\frac{-\sin\left(-x\right)}{\cos\left(-x\right)}$

$=\frac{-\cdot-\sin\left(x\right)}{\cos\left(x\right)}$

$=\frac{\sin\left(x\right)}{\cos\left(x\right)}$

$=\tan\left(x\right)$

Hence final answer is

$\frac{\cos\left(2x\right)-\cos\left(4x\right)}{\sin\left(2x\right)+\sin\left(4x\right)}=\tan\left(x\right)$

6 0

2 years ago

Dissimilar to similar fractions

V125BC [204]

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2. 7/9 and 6/9

3. 16/24 and 3/24

4. 3/12 and 8/12

5. 25/30 and 18/30

4 0

2 years ago

Molly has a $2500 down payment saved for this purchase, and the dealer’s $1500 Cash Allowance will come straight off her total.

babunello [35]

Answer: $\$\ 1000$

Step-by-step explanation:

Given

Molly down payment $=\$\ 2500$

Dealer's allowance $=\$\ 1500$

For loan amount , It is equal to the difference of molly down payment and dealer allowance

loan amount $=2500-1500$

loan amount $=\$\ 1000$

So, Molly needs $\$\ 1000$ loan

8 0

2 years ago

Can someone please help me with this?!

Maksim231197 [3]

Answer:

C. 39.6

good luck, i hope this helps :)

8 0

3 years ago

Put these in order starting with the smallest. 9 3/2 27 1/3 125 2/3

Pepsi [2]

Answer:

second, third,first

Step-by-step explanation:

first

3/2=1.5

9^1.5=27

second

1/3=0.333

27^0.333=3

third

2/3=0.667

125^0.667=25

3 0

2 years ago