Question for-th
- For the first line in the system:
- The line slants gradually down from left to right.
- The line passes through the following points:
- (negative 4 comma 5)
- (0 comma 4)
- (8 comma 2)
- For the second line in the system:
- The line is horizontal.
- The line passes through the following points:
- (0 comma 2)
- (8 comma 2)
If a new graph of three linear equations is created using the system of equations shown and the equation , how many solutions will the resulting system of three equations have?
Zero
Exactly one
Exactly two
Infinitely many
For the first line in the system: The line slants gradually down from left to right.
Hard-difficulty · SAT Math · Systems of Two Linear Equations — Graphical solution of two lines. 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. A solution to a system of equations must satisfy each equation in the system. It follows that if an ordered pair is a solution to the system, the point lies on the graph in the xy-plane of each equation in the system. The only point that lies on each graph of the system of two linear equations shown is their intersection point . It follows that if a new graph of three linear equations is created using the system of equations shown and the graph of , this system has either zero solutions or one solution, the point . Substituting for and for in the equation yields , or . Since this equation is not true, the point does not lie on the graph of . Therefore, is not a solution to the system of three equations. It follows that there are zero solutions to this system.
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.
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