Question

Find 4 numbers in ap sum is 20 and the sum of their square is 128 find number

Answer 1

Answer:

Let the four numbers be a-3d,a-d,a+d,a+3d

a-3d+a-d+a+d+a+3d=20

4a=20

a=5

(a-3d)^2+(a-d)^2+(a+d)^2+(a+3d)^2=128

(5-3d)^2+(5-d)^2+(5+d)^2+(5+3d)^2=128

25+9d^2-30d+25+d^2-10d+25+d^2+10d+25+9d^2+30d=128

100+20d^2=128

20d^2=28

d=√14/5

Step-by-step explanation:

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