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# If y is 1 more than the square of a positive number x, what is the val

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
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If y is 1 more than the square of a positive number x, what is the val  [#permalink]

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25 Jul 2017, 01:26
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5% (low)

Question Stats:

88% (00:46) correct 12% (01:43) wrong based on 57 sessions

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If y is 1 more than the square of a positive number x, what is the value of x, in terms of y?

$$A. x=\sqrt{y-1}$$
$$B. x=\sqrt{y+1}$$
$$C. x=2\sqrt{y-1}$$
$$D. x=2\sqrt{y+1}$$
$$E. x=y-1$$

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"Only $149 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Senior PS Moderator Joined: 26 Feb 2016 Posts: 3386 Location: India GPA: 3.12 If y is 1 more than the square of a positive number x, what is the val [#permalink] ### Show Tags 25 Jul 2017, 02:50 1 1 From the question stem, $$y = x^2 + 1$$ Therefore, $$x^2 = y - 1$$ or $$x=\sqrt{y-1}$$(Option A) Method 2(Assuming numbers) From the question stem, $$y = x^2 + 1$$ If x = 5, y = $$x^2 + 1 = 25+1 = 26$$ Only Option A($$\sqrt{y-1} = \sqrt{26-1} = \sqrt{25} = 5$$) gives us the same value of x when we substitute the value of y. _________________ You've got what it takes, but it will take everything you've got Target Test Prep Representative Status: Founder & CEO Affiliations: Target Test Prep Joined: 14 Oct 2015 Posts: 5807 Location: United States (CA) Re: If y is 1 more than the square of a positive number x, what is the val [#permalink] ### Show Tags 26 Jul 2017, 16:31 MathRevolution wrote: If y is 1 more than the square of a positive number x, what is the value of x, in terms of y? $$A. x=\sqrt{y-1}$$ $$B. x=\sqrt{y+1}$$ $$C. x=2\sqrt{y-1}$$ $$D. x=2\sqrt{y+1}$$ $$E. x=y-1$$ We can create the following equation: y = 1 + x^2 y - 1 = x^2 √(y - 1) = x Answer: A _________________ # Scott Woodbury-Stewart Founder and CEO Scott@TargetTestPrep.com 122 Reviews 5-star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 7230 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: If y is 1 more than the square of a positive number x, what is the val [#permalink] ### Show Tags 27 Jul 2017, 17:57 ==> From $$y=1+x^2$$ and $$x^2=y-1, x=\sqrt{y-1}$$, the answer is A. Answer: A _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$149 for 3 month Online Course"
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Re: If y is 1 more than the square of a positive number x, what is the val   [#permalink] 27 Jul 2017, 17:57
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