Question

Which of the following uses the substitution method to solve linear-quadratic system y=x2−4x+8
, y=3x−4
?(1 point)

(3,5)


(−4,−16)
and (−3,−13)


(4,8)
and (3,5)


(4,8)

Answer 1

Substitute y = 3x − 4 into y = x^2 − 4x + 8:

3x − 4 = x^2 − 4x + 8
0 = x^2 − 7x + 12
0 = (x − 3)(x − 4)

So x = 3 or x = 4. Then y = 3(3) − 4 = 5 and y = 3(4) − 4 = 8.

Solutions: (3, 5) and (4, 8).