Find the sum of the abscissas of the intersection points of the graphs of the function y = 7x-8 and y = x².
February 19, 2021 | education
| Find the coordinates of the intersection points of the given functions.
To do this, we equate the right-hand sides of the formulas and solve the equation.
x² = 7x – 8.
We transform the equation: we transfer all the terms to the left side of the equation and write the polynomial in the standard form.
We solve the quadratic equation using the formula through the discriminant.
x² – 7x + 8 = 0.
D = 49 – 32 = 17.
√D = √17.
x1,2 = (7 ± √17) / 2.
x1 = 3.5 + √17 / 2 and x2 = 3.5 – √17 / 2 are the abscissas of the intersection points of the graphs.
x1 + x2 = 3.5 + √17 / 2 + 3.5 – √17 / 2 = 3.5 + 3.5 = 7.
Answer: 7.
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