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If (2x + 1)^2 = 100, then which one of the following COULD e

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If (2x + 1)^2 = 100, then which one of the following COULD e [#permalink]  18 Apr 2018, 12:02
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If $$(2x + 1) ^2 = 100$$, then which one of the following COULD equal x ?

(A) $$\frac{-11}{2}$$

(B) $$\frac{-9}{2}$$

(C) $$\frac{11}{2}$$

(D) $$\frac{13}{2}$$

(E) $$\frac{17}{2}$$
[Reveal] Spoiler: OA

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Re: If (2x + 1)^2 = 100, then which one of the following COULD e [#permalink]  19 Apr 2018, 00:15
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Consider (2x + 1) as Y
We are given
Y^2 = 100
Therfore,
Y = + 10 or -10

That is
2x + 1 = 10
2x = 9
x = 9/2

OR

2x + 1 = -10
2x = -11
x = -11/2

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Re: If (2x + 1)^2 = 100, then which one of the following COULD e [#permalink]  17 Jul 2018, 12:36
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Carcass wrote:
If $$(2x + 1) ^2 = 100$$, then which one of the following COULD equal x ?

(A) $$\frac{-11}{2}$$

(B) $$\frac{-9}{2}$$

(C) $$\frac{11}{2}$$

(D) $$\frac{13}{2}$$

(E) $$\frac{17}{2}$$

Given

( 2x +1 )^2 = 100

2x + 1 = 10 or -10

So, x has to 2 different values.

2x +1 = 10

x = 9/2

or

2x + 1 = -10

2x = -11

x = -11/2.

Re: If (2x + 1)^2 = 100, then which one of the following COULD e   [#permalink] 17 Jul 2018, 12:36
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