Question

Determine the points of intersection of the line y = -2x + 7 and the parabola y = 2x2 + 3x - 5.

Answer 1

Answer:

Step-by-step explanation:

The x-values of those points can be found by equating the expressions for y, then solving for x.

... -2x +7 = 2x² +3x -5

... 2x² +5x -12 = 0 . . . . . . . . subtract the left side to put into standard form

This can be factored by looking fro two factors of 2·(-12) = -24 that add to give 5, the x-coefficient. Those factors are 8, -3.

... 2x² +8x -3x -12 = 0 . . . . rewrite the middle term

... 2x(x +4) -3(x +4) = 0 . . . factor by pairs

... (x +4)(2x -3) = 0 . . . . . . . complete factorization

... x = -4, x = 3/2 . . . . . . . . values of x that make the factors be zero

The corresponding y-values are ...

... for x = -4, y = -2(-4) +7 = 15

... for x = 3/2, y = -2(3/2) +7 = 4

The points of intersection are (-4, 15) and (3/2, 4).