2x2+x-21=0

Simple and best practice solution for 2x2+x-21=0 equation. Check how easy it is, and learn it for the future. Our solution is simple, and easy to understand, so don`t hesitate to use it as a solution of your homework.

If it's not what You are looking for type in the equation solver your own equation and let us solve it.

Solution for 2x2+x-21=0 equation:



2x^2+x-21=0
a = 2; b = 1; c = -21;
Δ = b2-4ac
Δ = 12-4·2·(-21)
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-13}{2*2}=\frac{-14}{4} =-3+1/2 $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+13}{2*2}=\frac{12}{4} =3 $

See similar equations:

| 14+3y=18-5y | | 7k–(k+6)+2k=2 | | 3(10x-8)=2(15x+12) | | 12=p-(-12) | | 4x-6(x-2)=7x+2 | | -5(-10+3x)=50 | | -4(8+r)=-28 | | -47=5z–17 | | 23=5n+8 | | 6(-3m+1)=26+2m | | 1/2m+3-5/6m=-15 | | 12u-5u=14 | | -3x+11=2x+7 | | 3(2x-6)=(5x-10) | | 3(x=1)-5=3x-2 | | 4​​3​​+b=​4​​7​​ | | 3/11x-2/5x=9/5x-4/11 | | 2v-10=-6 | | 7-2x=10-5x | | 3/11x+4/x=2/5x+9/5 | | 2y+2=7y-54 | | 2h+2=220 | | 1.7=-11.1+8u | | 12+-3b;b=4.3 | | 7(x-3)-3(x+4)=7+2(3x-8) | | 8(b+1)+4=3(2b-8) | | (11x-5)2=77 | | 2(15x)=20x+10 | | 0=x(2)-15x+36 | | 3+y/18.75=6 | | 2h+4=254 | | 27-11y=13 |

Equations solver categories