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Kruka [31]
2 years ago
10

Given the sum s20= 910 of an arithmetic sequence and A20 = 95, Find A1​

Mathematics
1 answer:
Inessa05 [86]2 years ago
5 0

Step-by-step explanation:

Sn=n/2(2a+(n-1)d)

910=n/2{2a+(n-1)d}

1820=n{2a+(n-1)d}

1820=20{2a+(20-1)d}

1820=20{2a+19d}

91=2a+19d

An=a+(n-1)d

95=a+(20-1)d

95=a+19d

91=2a+19d

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

4=-a

a=-4

91=2a+19d

91=2(-4)+19d

91=-8+19d

91+8=19d

99=19d

d=99/19

A=-4

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Jesse drank 3/4 of liter of water Monday before going jogging. He drank 3/5 of a liter of water after his jog. How much water di
charle [14.2K]

Answer:

1\frac{7}{20}

Step-by-step explanation:

Step one

Given data

On  Monday, Jesse drank 3/4 of liter of water before jogging

and drank 3/5 of liter after jogging

In all, Jesse drank 3/4 and 3/5 liters of water

= 3/4+3/5

the lcm is 20

=15+12/20

=27/20

in mixed numbers(i.e a whole and a fraction together we have) we have

1\frac{7}{20}

8 0
3 years ago
Lettets a, b, c, and d are angle measures Which should equal 105 to prove false g
GrogVix [38]

Answer:

a equals 105°

Step-by-step explanation:

angles in a straight line add up to 180°

a+75=180

a=180-75

a=105°

4 0
3 years ago
25 POINTS AND BRAINLIEST
kondor19780726 [428]

Answer:

4.24 hours

Step-by-step explanation:

Irina can paint 1/9 of a room in 1 hour since she can paint a room in 9 hours. 1/9x, where x is the number of hours she works and 1/9 of a room per hour is her speed, would be her part of the calculation.

Paulo can paint 1/8 of a room in 1 hour since he can paint an entire room in 8 hours. 1/8x, where x is the number of hours he works and 1/8 of a room per hour is his speed, would be his part of the equation.

1/9x + 1/8x = 1 (Irina's portion of the room plus Paulo's portion of the room equals one complete room) would be the equation.

Look for a denominator that has the same value as the numerator. Both 9 and 8 split evenly into 72 as the initial number. We multiply the top of 1/9 by 8 to convert the fraction and get 8/72x because 9*8 = 72. We multiply the top of 1/8 by 9 to convert the fraction and get 9/72x because 8*9 = 72. We have 8/72x+9/72x=1 currently.

17/72x=1

÷ both sides by 17/72:

17/72x ÷ 17/72 = 1÷17/72

∴ x=1/1 * 72/17

∴ x=72/17= 4.24

8 0
2 years ago
Answer this question please and thank you
Fiesta28 [93]

Answer:

7/8 to the 7th power

Step-by-step explanation:

4 0
3 years ago
Read 2 more answers
Who knows how to problem solve this this problem?
aleksandr82 [10.1K]

Answer:

just do it by Pythagoras theoram

Step-by-step explanation:

because it is a right angle

3 0
3 years ago
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