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2 years ago

Solve the equation x2-81 = 0.

Mathematics

2 answers:

Natasha2012 [34]2 years ago

7 0

Answer:

40.5

Step-by-step explanation:

x2 - 81 = 0 --> + 81 to both sides

2x = 81 --> divide by 2 on both sides

x = 40.5

vekshin12 years ago

5 0

Answer:

2x-81=0

2x=0+81

2x=81

x=81

x=40.5 ANSWER.

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Kathy is fencing in her yard that has an area of 800 square feet. Her yard is in the shape of a rectangle where the length is 60

anygoal [31]

Answer:

The dimensions of the yard are W=20ft and L=40ft.

Step-by-step explanation:

Let be:

W: width of the yard.

L:length.

Now, we can write the equation of that relates length and width:

$L=5W-60$ (Equation #1)

The area of the yard can be expressed as (using equation #1 into #2):

$Area=W*L=W*(5W-60)$ (Equation #2)

Since the Area of the yard is $800 ft^2$ , then equation #2 turns into:

$800=W*(5W-60)$

Now, we rearrange this equation:

$800=W*(5W-60)//800=5W^2-60W//5W^2-60W-800=0$

We can divide the equation by 5 :

$W^2-12W-160=0$

We need to find the solution for this quadratic. Let's find the factors of 160 that multiplied yields -160 and added yields -12. Let's choose -20 and 8, since $(-20)*8=160$ and $-20+8=-12$ . The equation factorised looks like this:

$(W-20)(W+8)=0$

Therefore the possible solutions are W=20 and W=-8. We discard W=-8 since width must be a positive number. To find the length, we substitute the value of W in equation #1:

$5*20-60=40$

Therefore, the dimensions of the yard are W=20ft and L=40ft.

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2 years ago

Colton is going to invest $76,000 and leave it in an account for 15 years. Assuming the interest is compounded daily, what inter

olga2289 [7]

Answer: 4.75%

Step-by-step explanation:

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2 years ago

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Yakvenalex [24]

The answer to your question is 3k^2m^6/4

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2 years ago

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Jet001 [13]

Answer:

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Step-by-step explanation:

Put the equation into y = mx + b form, by first isolating y:

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y = -9/7x + 1

So, -9/7 is the slope.

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2 years ago

Read 2 more answers

Which expression is equal to 2√ -32 ? 8i√2 −8√2 8√2i −8i√2

saw5 [17]

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2 years ago