Question

(no links or files) Solve this equation using the quadratic formula. This question should be solved both ways. (1) Quadratic Formula and (2) Factoring

Answer 1

Quadratic formula is x = -b+ or- sq rt b^2-4ac / 2a
a=2 b=5 c=-3
-5 +or- sqrt 5^2-4(2)(-3) / 2(2)
-5 +or- sqrt 49/ 4
-5 + 7 /4 = 2/4 = 1/2
-5 - 7 /4 = -12/4 = -3

Factoring a*c is 2*-3 =-6
Factors of -6 that add to 5 are 6 and -1
Split 5x into +6x-1x
2x^2+6x-1x-3 and group
2x(x+3)-1(x+3)
(x+3)(2x-1)=0
x+3=0 gives x=-3
2x-1=0 gives x=1/2