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# Question 23 of 30

beginning of content:

# M:C:MC:19

Tags:
SAT

Exam

Calculator: Permitted

Subscore

If  is a solution to the system of equations above, what is the value of

-51

No

3

No

9

Yes

144

No

Choice C is correct. The second equation gives y in terms of x, so a student can use this to rewrite the first equation in terms of x. Substituting -4x for y in the equation  gives  This can be simplified to  or  Since the question asks for the value of  not x, dividing both sides of  by 17 gives the answer:

Choice A is not the correct answer. This answer may result from neglecting to square the coefficient –4 in  which would give  Then the first equation would become  which would give –51 as the value of

Choice B is not the correct answer. This answer may result from finding the value for x, not the value of

Choice D is not the correct answer. This answer may result from finding the value of  not

Question Difficulty:
medium
Objective:

Students must manipulate one equation for use in another, in order to solve for a given value, making use of familiar algebraic arrangements where appropriate.