Question x-y-3-

1.3 Linear Equations in Two Variables - Writing equations from data/points
0:00
x y
3 7
k 11
12 n

The table above shows the coordinates of three points on a line in the xy-plane, where k and n are constants. If the slope of the line is 2, what is the value of k plus n ?

Enter your answer:

x y 3 7 k 11 12 n The table above shows the coordinates of three

Hard-difficulty · SAT Math · Linear Equations in Two Variables — Writing equations from data/points. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

The correct answer is 30. The slope of a line can be found by using the slope formula, the fraction with numerator y sub 2 minus y sub 1, and denominator x sub 2 minus x sub 1, end fraction. It’s given that the slope of the line is 2; therefore, the fraction with numerator y sub 2 minus y sub 1, and denominator x sub 2 minus x sub 1, end fraction, equals 2. According to the table, the points with coordinates 3 comma 7 and with coordinates k comma 11 lie on the line. Substituting the coordinates of these points into the equation gives the fraction with numerator 11 minus 7, and denominator k minus 3, end fraction, equals 2. Multiplying both sides of this equation by k minus 3 gives 11 minus 7, equals, 2 times, open parenthesis, k minus 3, close parenthesis, or 11 minus 7, equals, 2 k minus 6. Solving for k gives k equals 5. According to the table, the points with coordinates 3 comma 7 and with coordinates 12 comma n also lie on the line. Substituting the coordinates of these points into the fraction with numerator y sub 2 minus y sub 1, and denominator x sub 2 minus x sub 1, end fraction, equals 2 gives the fraction with numerator n minus 7, and denominator 12 minus 3, end fraction, equals 2. Solving for n gives n equals 25. Therefore, k plus n, equals, 5 plus 25, or 30.