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irakobra [83]
3 years ago
6

Easy math, but not sure what I did wrong.

Mathematics
1 answer:
Ierofanga [76]3 years ago
4 0

Answer:

8

Step-by-step explanation:

In his 5th year, he took 3 times as many exams as the first year.  So the number of exams taken in the 5th year must be a multiple of 3.

If a₁ = 1, then a₅ = 3.  However, this isn't possible because we need 4 integers between them, and a sum of 31.

If a₁ = 2, then a₅ = 6.  Same problem as before.

If a₁ = 3, then a₅ = 9.  This is a possible solution.

If a₁ = 4, then a₅ = 12.  If we assume a₂ = 5, a₃ = 6, and a₄ = 7, then the sum is 34, so this is not a possible solution.

Therefore, Alex took 3 exams in his first year and 9 exams in his fifth year.  So he took 19 exams total in his second, third, and fourth years.

3 < a₂ < a₃ < a₄ < 9

If a₂ = 4, then a₃ = 7 and a₄ = 8.

If a₂ = 5, then a₃ = 6 and a₄ = 8.

If a₂ = 6, then there's no solution.

So Alex must have taken 8 exams in his fourth year.

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Connie is packing for a trip. She has 17 pairs of jeans. If she has room to pack 6 pairs how many ways can she choose which jean
Evgesh-ka [11]

Answer:12,376

Step-by-step explanation:

Given

Connie has 17 Pairs of jeans

She has to choose 6 pairs out of 17

We know, no of ways to pick r items out of n items is ^nC_r

\therefore \text{No of ways is =}^{17}C_6\\\\\Rightarrow \dfrac{17!}{(17-6)!6!}=12,376\ \text{ways}

6 0
3 years ago
ABCD diagonals intersect at E. If m∠BAC=4x+5 and m∠CAD=5x-14, then find m∠CAD.
Travka [436]

Answer: m∠CAD = 81°

Step-by-step explanation: <u>Diagonal</u> is a line that unites opposite sides.

ABCD is a prallelogram. One property of diagonal in a parallelogram is it separates the parallelogram in 2 congruent triangles.

The figure below shows ABCD with its diagonals.

Since diagonal divides a parallelogram in 2 congruent triangles, it means the internal angles are also congruent. So

m∠BAC = m∠CAD

4x + 5 = 5x - 14

x = 19

Then, m∠CAD is

m∠CAD = 5(19) - 14

m∠CAD = 81

The angle m∠CAD is 81°.

7 0
3 years ago
Suppose y=f(x)+k. what effect does k have on the parent function?
Aleksandr [31]
It moves it up and down

6 0
3 years ago
I need help again help me pllsssssss
notka56 [123]

Answer: you end up at (2,2)

Step-by-step explanation:

8 0
3 years ago
Read 2 more answers
Find an equation of the plane that contains the points p(5,−1,1),q(9,1,5),and r(8,−6,0)p(5,−1,1),q(9,1,5),and r(8,−6,0).
topjm [15]
Given plane passes through:
p(5,-1,1), q(9,1,5), r(8,-6,0)

We need to find a plane that is parallel to the plane through all three points, we form the vectors of any two sides of the triangle pqr:
pq=p-q=<5-9,-1-1,1-5>=<-4,-2,-4>
pr=p-r=<5-8,-1-6,1-0>=<-3,5,1>

The vector product pq x pr gives a vector perpendicular to both pq and pr.  This vector is the normal vector of a plane passing through all three points
pq x pr
=
  i   j   k
-4 -2 -4
-3  5  1
=<-2+20,12+4,-20-6>
=<18,16,-26>

Since the length of the normal vector does not change the direction, we simplify the normal vector as
N = <9,8,-13>

The required plane must pass through all three points.
We know that the normal vector is perpendicular to the plane through the three points, so we just need to make sure the plane passes through one of the three points, say q(9,1,5).

The equation of the required plane is therefore
Π :  9(x-9)+8(y-1)-13(z-5)=0
expand and simplify, we get the equation
Π  :  9x+8y-13z=24

Check to see that the plane passes through all three points:
at p: 9(5)+8(-1)-13(1)=45-8-13=24
at q: 9(9)+8(1)-13(5)=81+9-65=24
at r: 9(8)+8(-6)-13(0)=72-48-0=24
So plane passes through all three points, as required.

3 0
3 years ago
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