If a + b = 7 and ab = 10; the value of a^2 + b^2 is equal to: 1. 29 2. 49 3. 39 4. 69

Using the formula, [∵(x \+ y) 2 = x 2 \+ 2xy \+ y 2 ] So, (a \+ b) 2 = a 2 \+ 2ab \+ b 2 Putting the value, a \+ b = 7 and ab = 10 ⇒ (7) 2 = a 2 \+ 2 x 10 \+ b 2 ⇒ 49 = a 2 \+ 20 \+ b 2 ⇒ a 2 \+ b 2 = 49 \- 20 ⇒ a 2 \+ b 2 = 29 Hence, option 1 is the correct option.

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Mathematics

If a + b = 7 and ab = 10; the value of a² + b² is equal to:
29
49
39
69

Identities

3 Likes

Answer

Using the formula,

[∵(x + y)² = x² + 2xy + y²]

So,

(a + b)² = a² + 2ab + b²

Putting the value, a + b = 7 and ab = 10

⇒ (7)² = a² + 2 x 10 + b²

⇒ 49 = a² + 20 + b²

⇒ a² + b² = 49 - 20

⇒ a² + b² = 29

Hence, option 1 is the correct option.

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1 Like

Mathematics

If a + b = 7 and ab = 10; the value of a² + b² is equal to:
29
49
39
69

Identities

Answer

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