Loading web-font TeX/Math/Italic

X2+21x+90=0

Simple and best practice solution for X2+21x+90=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 X2+21x+90=0 equation: 



X2+21X+90=0

We add all the numbers together, and all the variables

X^2+21X+90=0

a = 1; b = 21; c = +90;
Δ = b2-4ac
Δ = 212-4·1·90
Δ = 81
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{81}=9


X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-9}{2*1}=\frac{-30}{2}
=-15



X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+9}{2*1}=\frac{-12}{2}
=-6

See similar equations:

| (x^2-2x+3)=(x^2-3) | | T2-4t-12=0 | | 5x^2*(x-1)=10x-10 | | 4.16+.75x=5.66+.5x | | 2-x=x-18 | | 3x+7(x+1)=2(6x+5)-2x | | 0.16(y-2)+0.20y=0.08y-2.7 | | 4y=-8y+36 | | (x+7)=(2x+4) | | -51+x/3=-9 | | 4t2-4t+1=0 | | -5-7y=-20+34 | | 19.2x-15=7.5+8.3 | | 0.2=x/10 | | 30+6.25x=12+9.75x | | 4x+21=5x+37 | | -t2+2t-1=0 | | 4y/4y=2 | | 5y+18y+2y+-10y=19y | | T2-20t+100=0 | | 6(5x-3)+2=15 | | 2x+3x=5x+2x | | 2T2-8t+8=0 | | -1.4y=5.6 | | (x^2+12x+12)=(x+2) | | x.308=22x | | -1.4y=4.2 | | 10x22=29-7x | | (x^2+2x+4)=(x^2-9) | | 3x=36;x=6 | | 6(x−11)=15−4x | | -w+5=0 |

Equations solver categories