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dhr

· started a discussion

· 1 Months ago

after multipling both eq how to get 2a squre b squre - a squre b squre

Question:

If  a2+b2+ab=7 and a2+b2-ab=5   then find the value of  a4+b4+a2b2.   

Options:
A)

25

B)

35

C)

12

D)

74

Solution:

a2+b2+ab=7   ……..(i)

a2+b2-ab=5   ….…(ii)

Equation (i) × (ii)

Then  a4+b4+2a2b2-a2b2=35   

a4+b4+a2b2=35   

Knowledge Expert

· commented

· 1 Months ago

Dear Student,
Simple multiplication rule is being followed here.
The given answer is correct.
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Team Toprankers

Knowledge Expert

· commented

· 1 Months ago

Dear student,
(a^2+b^2+ab)x(a^2+b^2-ab)= a^4+b^4+ a^4+b^4+a^2b^2+a^2b^2−a^2b^2
=a^4+b^4+ a^4+b^4+2(a^2b^2)+−a^2b^2
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