If x-1 is a common root of the equation x2-a x-3-0 and b x2-7 x-2-0 then a b-A- 10B- -3C- 7D- 6

The correct option is A 10x = 1 is a common root of the equation x2 + ax 3 = 0 and bx2 7x + 2 = 0 12 + a.1 3 =0 , hence a = 2 b.12 7.1 + 2 =0 , hence ...

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Standard XII

Mathematics

Composite Function

If x=1 is a c...

Question

If x = 1 is a common root of the equation x² + ax - 3 = 0 and bx² - 7x + 2 = 0 then ab =

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Solution

The correct option is A
10

x = 1 is a common root of the equation x² + ax - 3 = 0 and bx² - 7x + 2 = 0
1² + a.1 - 3 =0 , hence a = 2

b.1² - 7.1 + 2 =0 , hence b = 5

ab = 2.5 = 10

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Similar questions

Q. If x = 1 is a common root of

a x^{2} + a x + 3 = 0 and x^{2} + x + b = 0, then a b = ?

(a) 3
(b) −3
(c) 4
(d) 6

Q. If x = 1 is a common roots of the equations ax² + ax + 3 = 0 and x² + x + b = 0, then ab =

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Q. If

x = 1

is common root of equations

a x^{2} + a x + 3 = 0

and

x^{2} + x + b = 0

, then value of

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will be:

Q. If x = 1 is a common root of ax² + ax + 2 = 0 and x² + x + b = 0, then, ab =

(a) 1
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Q. Assertion :If the equation

x^{2} + b x + c a = 0

and

x^{2} + c x + a b = 0

have a common root, then their other root will satisfy the equation

x^{2} + a x + b c = 0

Reason: If the equation

x^{2} = b x + c a = 0

and

x^{2} + c x + a b = 0

have a common root, then

a + b + c = 0

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If x = 1 is a common root of the equation x2 + ax - 3 = 0 and bx2 - 7x + 2 = 0 then ab =

The correct option is A 10x = 1 is a common root of the equation x2 + ax - 3 = 0 and bx2 - 7x + 2 = 0 12 + a.1 - 3 =0 , hence a = 2 b.12 - 7.1 + 2 =0 , hence b = 5 ab = 2.5 = 10

If x = 1 is a common root of the equation x² + ax - 3 = 0 and bx² - 7x + 2 = 0 then ab =

The correct option is A
10

x = 1 is a common root of the equation x² + ax - 3 = 0 and bx² - 7x + 2 = 0
1² + a.1 - 3 =0 , hence a = 2

b.1² - 7.1 + 2 =0 , hence b = 5

ab = 2.5 = 10