Algebra
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If p × q = p + q + p , the value of 8 × 2 is : q
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p × q = p + q + p q ∴ 8 × 2 = 8 + 2 + 8 2
=10 + 4 = 14Correct Option: C
p × q = p + q + p q ∴ 8 × 2 = 8 + 2 + 8 2
=10 + 4 = 14
- If a * b = 2a – 3b + ab, then 3 * 5 + 5 * 3 is equal to :
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a * b = 2a – 3b + ab
⇒ 3 * 5 = 2 × 3 – 3 × 5 + 3 × 5 = 6
5 * 3 = 2 × 5 – 3 × 3 + 3 × 5
= 10 – 9 + 15 = 16
Therefore, 3 * 5 + 5 *3
= 6 + 16 = 22Correct Option: A
a * b = 2a – 3b + ab
⇒ 3 * 5 = 2 × 3 – 3 × 5 + 3 × 5 = 6
5 * 3 = 2 × 5 – 3 × 3 + 3 × 5
= 10 – 9 + 15 = 16
Therefore, 3 * 5 + 5 *3
= 6 + 16 = 22
- If p(x + y)2 = 5 and q(x - y)2 = 3 , then the simplified value of p2 (x + y)2 + 4pq xy – q2 (x - y)2 is :
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p(x + y)2 = 5
⇒ (x + y)2 = 5 p ⇒ q(x - y)2 = 3 ⇒ (x - y)2 = 3 q ∴ (x + y)2 - (x - y)2 = 5 - 3 p q ⇒ 4xy = 5 - 3 = 5q - 3p p q pq ∴ p2 (x + y)2 + 4pq xy – q2 (x - y)2 = p2 . 5 + pq. (5q - 3p) - q2 . 3 p pq q
p2 (x + y)2 + 4pq xy – q2 (x - y)2 = 5p + 5q – 3p – 3q = 2p + 2qCorrect Option: B
p(x + y)2 = 5
⇒ (x + y)2 = 5 p ⇒ q(x - y)2 = 3 ⇒ (x - y)2 = 3 q ∴ (x + y)2 - (x - y)2 = 5 - 3 p q ⇒ 4xy = 5 - 3 = 5q - 3p p q pq ∴ p2 (x + y)2 + 4pq xy – q2 (x - y)2 = p2 . 5 + pq. (5q - 3p) - q2 . 3 p pq q
p2 (x + y)2 + 4pq xy – q2 (x - y)2 = 5p + 5q – 3p – 3q = 2p + 2q
- If x = ³√7 + 3 then the vlaue of x3 - 9x2 + 27x - 34 is :
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x = ³√7 + 3
⇒ x - 3 = ³√7
On cubing both sides ,
(x - 3)3 = (³√7)3
⇒ x3 - 3.x2.3 + 3.x.(3)2 - (3)3 = 7
⇒ x3 - 9x2 + 27x - 27 = 7
⇒ x3 - 9x2 + 27x - 34 = 0Correct Option: A
x = ³√7 + 3
⇒ x - 3 = ³√7
On cubing both sides ,
(x - 3)3 = (³√7)3
⇒ x3 - 3.x2.3 + 3.x.(3)2 - (3)3 = 7
⇒ x3 - 9x2 + 27x - 27 = 7
⇒ x3 - 9x2 + 27x - 34 = 0
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If c + 1 = 3 , then the value of (c - 3)7 + 1 is c c7
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c + 1 = 3 c ⇒ c - 3 = - 1 c ∴ (c - 3)7 + 1 = - 1 7 + 1 c7 c c7 Required answer = - 1 + 1 = 0 c7 c7
Correct Option: B
c + 1 = 3 c ⇒ c - 3 = - 1 c ∴ (c - 3)7 + 1 = - 1 7 + 1 c7 c c7 Required answer = - 1 + 1 = 0 c7 c7