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OG 11 #98

This topic has 1 expert reply and 4 member replies

OG 11 #98

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If x(2x+1)=0 and (x+1/2)(2x-3)=0 then x=

A) -3
B) -1/2
C) 0
D) 1/2
E) 3/2

Answer is 0 or -1/2?

As a linear equation x(2x+1) can give both 0 and -1/2 right?

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singalong wrote:
If x(2x+1)=0 and (x+1/2)(2x-3)=0 then x=
From x(2x + 1) = 0, we have either x = 0 or x = -1/2

For, x = 0, (x + 1/2)(2x - 3) = -3/2 ---> Doesn't satisfy equation 2
for x = -1/2, (x + 1/2)(2x - 3) = 0 ---> Satisfies equation 2

Hence, x = -1/2

The correct answer is B

Quote:
As a linear equation x(2x+1) can give both 0 and -1/2 right?
x(2x + 1) = 0 is not a linear equation, it's a quadratic equation.

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x should be -1/2 as it satisfies both the quadratic equations.

Hence answer should be B

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thanks

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singalong ... the best way to solve this question is to plug the answer choices into the question to see which answer choice satisfies both equations: -1/2 satisfies both equations IMO B is the way to go here

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B: -1/2

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