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Can someone explain in detail how to solve the problem

Help 30 points Can someone explain in detail how to solve the problem-example-1
User Aleclarson
by
8.2k points

1 Answer

4 votes
well


aritmetic is
an=a1+d(n-1)
so

first will be a1
7th is a1+6d

4th is a1+3d

let's say that a1=x and d=y for niceness sake

so

sum of first and 7th is 40
x+x+6y=40
2x+6y=40
divide 2
x+3y=20


product of first and 4th is 160
x times (x+3y)=160
hold a sec, from previous problem, x+3y=20
x times 20=160
divide both sides by 20
x=8

sub back

x+3y=20
8+3y=20
minus 8 both sides
3y=12
divide by 3
y=4


an=8+4(n-1) is da equation
to find the terms, subsitute
frst is 8
2nd is 12
etc
the first 8 terms are
8,12,16,20,24,28,32,36
User Skaue
by
8.6k points

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