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SAT Math Question for the week of 08/15/2021

What is the x-intercept of a line passing through the points (-1, 1.5) and (0, 4)?


Maps to Category 1 of the book.

 

Answer posted on 08/22/2021: Answer is -1.6 or -4/2.5.


Since x = 0 at y-intercept, the given point (0, 4) is the y-intercept of the line.

Determine the slope, and plug the slope and the y-intercept in the y = mx + b equation.


Slope = (4 - 1.5)/(0-(-1)) = 2.5/1 = 2.5.

Hence, the equation is y = 2.5x + 4.


Since y = 0 at x-intercept, set y = 0 in the above equation and solve for x.

0 = 2.5x + 4 --> 2.5x = -4 --> x = -4/2.5 = -1.6.


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