How do you solve 2x^2+x-1=9?

3 Answers
May 8, 2018

x=-5/2 or x=2x=52orx=2

Explanation:

2x^2+x-1=9 => 2x^2+x-10=02x2+x1=92x2+x10=0

(2x+5)(x-2)=0(2x+5)(x2)=0

2x+5=0 or x-2=02x+5=0orx2=0

2x=-5 or x=22x=5orx=2

x=-5/2 or x=2x=52orx=2

May 8, 2018

x=-5/2 , 2x=52,2

Explanation:

let,
2x^2+x-1-9=02x2+x19=0
2x^2-4x+5x-102x24x+5x10=0 (we get this by factorizing)
2x(x-2)+5(x-2)2x(x2)+5(x2)=0
(2x+5)(x-2)=0(2x+5)(x2)=0
thereforex= -5/2,2

May 8, 2018

x=-5/2 and x=2

Explanation:

Set equal to 0:

2x^2+x-1=9

rArr 2x^2+x-10=0

Factorise:

2x^2-4x+5x-10

rArr 2x(x-2)+5(x-2)

rArr (2x+5)(x-2)

Set equal to 0:

2x+5=0

rArr 2x=-5

rArr x=-5/2

x-2=0

rArrx=2