Question

If x + y = 3, x^2 + y^2 = 5 then xy is (Hint: use identity to solve )
(1 Point)
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Answer 1

Question:-

If x + y = 3, x² + y² = 5 then xy is

Solution:-

Given

• x + y = 3
• x² + y² = 5

x + y = 3

Now,

Squares on both sides.

Then,

➣ ( x + y )² = 3²

➣ x² + y² + 2ab = 9

➣ 5 + 2ab = 9

➣ 2ab = 9 - 5

➣ 2ab = 4

➣ ab = 4/2

➣ $\boxed{ \: ab \: = \: 2 \: }$

Verification:-

➣ x² + y² + 2ab = 9

➣ 5 + 2(2) = 9

➣ 5 + 4 = 9

➣ 9 = 9

Answer 2

Step-by-step explanation:

Question:-

If x + y = 3, x² + y² = 5 then xy is

Solution:-

Given

x + y = 3

x² + y² = 5

x + y = 3

Now,

Squares on both sides.

Then,

➣ ( x + y )² = 3²

➣ x² + y² + 2ab = 9

➣ 5 + 2ab = 9

➣ 2ab = 9 - 5

➣ 2ab = 4

➣ ab = 4/2

➣ ab = 2

Verification:-

➣ x² + y² + 2ab = 9

➣ 5 + 2(2) = 9

➣ 5 + 4 = 9

➣ 9 = 9