solve 15=2x^2-6x+8

Question

Please help me solve the problem 15 equals 2 x squared -6 x + 8

Answer 1

15 = 2x^2 - 6x + 8

0 = 2x^2 - 6x - 7

It doesn't factor nicely, so let's use the quadratic formula.

Note:  This may be unfair since you probably haven't been given this formula yet.  It lets you solve any 2nd-order (something with an x^2) equation.

(6 +- sqrt(36 + 56))/4

(6 +- sqrt(92))/4

(6 +- sqrt(4*23))/4

(6 +- 2sqrt(23))/4

(3 +- sqrt(23))/2

Answer:  x = (3+sqrt(23))/2 or x = (3-sqrt(23))/2