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Mekhanik [1.2K]
3 years ago
13

Which is the best first step and explanation for solving this system of equations?

Mathematics
2 answers:
wariber [46]3 years ago
7 0

Answer:

A ) subtract the second equation from the first equation

Step-by-step explanation:

2x + 3y = 7

2x - 4y = -5

subtracting the second equation from the first equation we get,

7y = 12

y=12/7

This is the correct option

denis-greek [22]3 years ago
5 0

Answer:

A ) subtract the second equation from the first equation

Step-by-step explanation:

Let's consider the following system of equations.

2x + 3y = 7

2x = 4y - 5

If we subtract the second equation from the first equation, we get:

2x + 3y - 2x = 7 - (4y - 5)

3y = 7 - 4y + 5

7y = 12

y = 12/7

Then, we can use any of the original equations and solve for x.

2x = 4y - 5

2x = 4(12/7) - 5

x = 13/14

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andrey2020 [161]

First observe that if a+b>0,

(a + b)^2 = a^2 + 2ab + b^2 \\\\ \implies a + b = \sqrt{a^2 + 2ab + b^2} = \sqrt{a^2 + ab + b(a + b)} \\\\ \implies a + b = \sqrt{a^2 + ab + b \sqrt{a^2 + ab + b(a+b)}} \\\\ \implies a + b = \sqrt{a^2 + ab + b \sqrt{a^2 + ab + b \sqrt{a^2 + ab + b(a+b)}}} \\\\ \implies a + b = \sqrt{a^2 + ab + b \sqrt{a^2 + ab + b \sqrt{a^2 + ab + b \sqrt{\cdots}}}}

Let a=0 and b=x. It follows that

a+b = x = \sqrt{x \sqrt{x \sqrt{x \sqrt{\cdots}}}}

Now let b=1, so a^2+a=4x. Solving for a,

a^2 + a - 4x = 0 \implies a = \dfrac{-1 + \sqrt{1+16x}}2

which means

a+b = \dfrac{1 + \sqrt{1+16x}}2 = \sqrt{4x + \sqrt{4x + \sqrt{4x + \sqrt{\cdots}}}}

Now solve for x.

x = \dfrac{1 + \sqrt{1 + 16x}}2 \\\\ 2x = 1 + \sqrt{1 + 16x} \\\\ 2x - 1 = \sqrt{1 + 16x} \\\\ (2x-1)^2 = \left(\sqrt{1 + 16x}\right)^2

(note that we assume 2x-1\ge0)

4x^2 - 4x + 1 = 1 + 16x \\\\ 4x^2 - 20x = 0 \\\\ 4x (x - 5) = 0 \\\\ 4x = 0 \text{ or } x - 5 = 0 \\\\ \implies x = 0 \text{ or } \boxed{x = 5}

(we omit x=0 since 2\cdot0-1=-1\ge0 is not true)

3 0
2 years ago
Lenny and Lisa have obtained a 30-year, fixed rate mortgage for $675,250 with a 7.25% interest rate. They purchased 3 points and
Vikentia [17]

Answer:

119 months

Step-by-step explanation:

In this question, we are asked to calculate the amount of time it would take for a break-even point on a mortgage, if there is a factoring in the cost of points.

We proceed to answer the;

Mathematically,

The Break Even Point = Amount Paid for purchasing Discount Points divided by Monthly savings in the interest payments

We lost out the important values given in the question as follows:

Amount of Mortgage - $675,250

Tenure - 30 Years

The Rate of interest without points = 7.25%

The number of points = 3 points

The rate of interest with the 3 points = 6.875%

The amount to be paid for purchasing the discount point is now calculated below;

Since 1 discount point = 1% of mortgage value;

Therefore, 3 discount points = 3% of mortgage value

The amount paid is thus = 3% of $675,250 = $20,257.5

To calculate Monthly payment without points, we use the mathematical formula;

M = P[r(1+r)^n/((1+r)^n)-1)]

Where M

Is monthly payment, r is the interest rate, n is the number of months.

According to the question M = 675,250, r = 7.25% = 7.25/100 = 0.0725 , n= 30 * 12 months = 360 months

M = 675,250[0.0725(0.0725+1)^30/(1+0.0725)^360)-1) = $4606.40

To get the monthly payment with points, we simply use the formula again but this time interest rates will be 6.875% = 0.06875 I.e r = 0.06875

Inputting the terms in the formula will yield a value of $4435.91. This means monthly payment with discount will be $4435.91

Savings in monthly payments after purchasing the discount points = $4,606.40 - $4,435.91 = $170.48

Break Even = Purchase cost of Discount Points / Monthly savings

= $20,257.5 / $170.48

= 119 Months

Hence, the number of months it will take Lisa and Lenny to break-even point on their mortgage will be 119 months

6 0
3 years ago
I don’t understand this equation please help me
Reika [66]

Answer:

Evaluated, you get 4x^4

Step-by-step explanation:

Differentiated, you get 16x^3

It all depends on what you're looking for, really

8 0
3 years ago
Evaluate the expression 3(7 + 4)2 − 14 ÷ 7. 50 361 363 586
Kipish [7]
It appears that none of your option choices are correct,, are you sure you copied them right ? I will show you how to solve this and how I got my answer.
The first step for solving this is to add the numbers in the parenthesis.
3 × 11 × 2 - 14 ÷ 7
Divide -14 by 7.
3 × 11 × 2 - 2
Divide the first 3 numbers together.
66 - 2
Subtract the numbers together to get your final answer.
64
Let me know if you have any further questions.
:)
4 0
3 years ago
Read 2 more answers
Please Help Brain list and 25 Points whoever gets it right. You have to have a actual explanation and a real answer. Not just B,
den301095 [7]

Answer: B

Step-by-step explanation:

9/6 divided by 3/2

you flip 3/2 to 2/3 and multiply

9/6 times 2/3 = 1

3 0
3 years ago
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