Question

Please solve this problem

Answer 1

Given, a+b=25 and ab=20
therefore, a=?
now,
b=25-a. ---1
now applying equation 1 in ab=20
a(25-a)=20
-a²+25a=20
-a²+25a-20=0
-(a²-25a+20)=0
a²-25a+20=0
now since it's in the form of ax²+bx+c=0, then it is a quadratic equation
Factorise it by quadratic formula.
x= -b+ or -√b²-4ac / 2a ( first by placing positive sign)
-(-25)+√625-4×1×20/2
25+√625-80 /2
25+√545/2
25+√545/2
and second value of a is 25-√545/2
so,
a=25+√545/2 and 25-√545/2

Answer 2

Given a+b=25 and ab=20

then,

a-b=±√(a+b)^2 -4ab

a-b=±√(25)^2-4x20

a-b=±√625-80

a-b=±√545

a-b=23.3

a+b=25(given)

a-b=±23.3

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

2a = 48.3

or

2a = 1.7

a = 48.3/2=24.15

or

a = 1.7/2=0.85

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