If a + b - c = 4 and a 2 + b 2 + c 2 = 14, the value of ab - bc - ca is : 1. 2 2. 1 3. 0.5 4. -0.5

By formula, ⇒ (a + b - c) 2 = a 2 + b 2 + c 2 + 2(ab - bc - ca) Substituting values we get : ⇒ 4 2 = 14 + 2(ab - bc - ca) ⇒ 16 = 14 + 2(ab - bc - ca) ⇒ 2(ab - bc - ca) = 16 - 14 ⇒ 2(ab - bc - ca) = 2 ⇒ ab - bc - ca = 1 Hence, Option 2 is the correct option.

Mathematics

If a + b - c = 4 and a² + b² + c² = 14, the value of ab - bc - ca is :
2
1
0.5
-0.5

Expansions

10 Likes

Answer

By formula,

⇒ (a + b - c)² = a² + b² + c² + 2(ab - bc - ca)

Substituting values we get :

⇒ 4² = 14 + 2(ab - bc - ca)

⇒ 16 = 14 + 2(ab - bc - ca)

⇒ 2(ab - bc - ca) = 16 - 14

⇒ 2(ab - bc - ca) = 2

⇒ ab - bc - ca = 1

Hence, Option 2 is the correct option.

Answered By

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Mathematics

If a + b - c = 4 and a² + b² + c² = 14, the value of ab - bc - ca is :
2
1
0.5
-0.5

Expansions

Answer

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Mathematics

If a + b - c = 4 and a2 + b2 + c2 = 14, the value of ab - bc - ca is :210.5-0.5

Expansions

Answer

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If a + b - c = 4 and a² + b² + c² = 14, the value of ab - bc - ca is :
2
1
0.5
-0.5

The expansion of (x - 3y)(x + 5y) is :
x² + 2xy + 15y²
x² + 2xy - 15y²
x² - 2xy + 15y²
x² - 2xy - 15y²

x² - (a + b)x + ab is the expansion of :
(x - b)(x - a)
(x - b)(x + a)
(x + b)(x - a)
(x + a)(x + b)