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4 years ago

Find the equation for the line that passes through -1,-2 and 4,3. Is the point 3,1 on the line

Mathematics

1 answer:

DaniilM [7]4 years ago

3 0

Answer:

y = x -1
no

Step-by-step explanation:

A graph quickly answers this question.

The given points have a horizontal difference of 4-(-1) = 5 and a vertical difference of 3-(-2) = 5, so the slope of the line between them is ...

m = Δy/Δx = 5/5 = 1

The point-slope form of the equation for a line can be written ...

y = m(x -h) +k . . . . . for slope m through point (h, k)

Using the first point and the slope we found, we can write the equation as ...

y = 1(x -(-1)) +(-2)

y = x -1 . . . . . . . . . simplify; this is the equation of the line

When we try the third point in this equation, we get ...

y = 3 -1 = 2 ≠ 1 . . . . . the third point is not on the line

You might be interested in

In how many years will the interest of a sum of rs 3600 at the rate of 5.5% per year be rs 594?

boyakko [2]

Answer:

In 3 years, the interest of a sum of rs 3600 at the rate of 5.5% per year be Rs 594.

Step-by-step explanation:

T = ?

R = 5.5%

P = Rs 3600

I = Rs 594

T = (I×100)/(P×R)

or, T = (594×100)/(3600×5.5)

or, T = 59400/19800

so, T = 3 yrs

7 0

3 years ago

7) PG & E have 12 linemen working Tuesdays in Placer County. They work in groups of 8. How many

BabaBlast [244]

Part A

Since order matters, we use the nPr permutation formula

We use n = 12 and r = 8

$_{n}P_{r} = \frac{n!}{(n-r)!}\\\\_{12}P_{8} = \frac{12!}{(12-8)!}\\\\_{12}P_{8} = \frac{12!}{4!}\\\\_{12}P_{8} = \frac{12*11*10*9*8*7*6*5*4*3*2*1}{4*3*2*1}\\\\_{12}P_{8} = \frac{479,001,600}{24}\\\\_{12}P_{8} = 19,958,400\\\\$

There are a little under 20 million different permutations.

<h3>Answer: 19,958,400</h3>

Side note: your teacher may not want you to type in the commas

============================================================

Part B

In this case, order doesn't matter. We could use the nCr combination formula like so.

$_{n}C_{r} = \frac{n!}{r!(n-r)!}\\\\_{12}C_{8} = \frac{12!}{8!(12-8)!}\\\\_{12}C_{8} = \frac{12!}{4!}\\\\_{12}C_{8} = \frac{12*11*10*9*8!}{8!*4!}\\\\_{12}C_{8} = \frac{12*11*10*9}{4!} \ \text{ ... pair of 8! terms cancel}\\\\_{12}C_{8} = \frac{12*11*10*9}{4*3*2*1}\\\\_{12}C_{8} = \frac{11880}{24}\\\\_{12}C_{8} = 495\\\\$

We have a much smaller number compared to last time because order isn't important. Consider a group of 3 people {A,B,C} and this group is identical to {C,B,A}. This idea applies to groups of any number.

-----------------

Another way we can compute the answer is to use the result from part A.

Recall that:

nCr = (nPr)/(r!)

If we know the permutation value, we simply divide by r! to get the combination value. In this case, we divide by r! = 8! = 8*7*6*5*4*3*2*1 = 40,320

So,

$_{n}C_{r} = \frac{_{n}P_{r}}{r!}\\\\_{12}C_{8} = \frac{_{12}P_{8}}{8!}\\\\_{12}C_{8} = \frac{19,958,400}{40,320}\\\\_{12}C_{8} = 495\\\\$