Question

if a2+b2=9and ab =4 find the value of 3(a+b)2-2(a-b)2

Answer 1

bro...my providing same method question...so check this....First, we can expand the first equation as:

(a+b)2=9

a2+2ab+b2=9

Next, we can expand the second equation as:

(a−b)2=49

a2−2ab+b2=49

Then, we can add the left side of each equation and the right side of each equation giving:

a2+2ab+b2+a2−2ab+b2=9+49

a2+a2+2ab−2ab+b2+b2=58

2a2+0+2b2=58

2a2+2b2=58

2(a2+b2)=58

2(a2+b2)2=582

2(a2+b2)2=29

a2+b2=29