Question 8-x-y-

2.3 Systems Involving Nonlinear Equations - Line + parabola intersections
0:00

8 x + y = -11

2 x 2 = y + 341

The graphs of the equations in the given system of equations intersect at the point (x , y ) in the x y -plane. What is a possible value of x ?

A.

-15

B.

-11

C.

2

D.

8

8 x + y = - 11 2 x 2 = y + 341 The graphs

Hard-difficulty · SAT Math · Systems Involving Nonlinear Equations — Line + parabola intersections. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice A is correct. It's given that the graphs of the equations in the given system of equations intersect at the point x,y. Therefore, this intersection point is a solution to the given system. The solution can be found by isolating y in each equation. The given equation 8x+y=-11 can be rewritten to isolate y by subtracting 8 x from both sides of the equation, which gives y=-8x-11. The given equation 2x2=y+341 can be rewritten to isolate y by subtracting 341 from both sides of the equation, which gives 2x2-341=y. With each equation solved for y , the value of y from one equation can be substituted into the other, which gives 2x2-341=-8x-11. Adding 8 x and 11 to both sides of this equation results in 2x2+8x-330=0. Dividing both sides of this equation by 2 results in x2+4x-165=0. This equation can be rewritten by factoring the left-hand side, which yields x+15x-11=0. By the zero-product property, if x+15x-11=0, then x+15=0, or x-11=0. It follows that x=-15, or x=11. Since only -15 is given as a choice, a possible value of x is -15. 

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.

Choice D is incorrect and may result from conceptual or calculation errors.