If it's not what You are looking for type in the equation solver your own equation and let us solve it.
-n^2-n+21=0
We add all the numbers together, and all the variables
-1n^2-1n+21=0
a = -1; b = -1; c = +21;
Δ = b2-4ac
Δ = -12-4·(-1)·21
Δ = 85
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-\sqrt{85}}{2*-1}=\frac{1-\sqrt{85}}{-2} $$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{85}}{2*-1}=\frac{1+\sqrt{85}}{-2} $
| -10-8r+4=-76 | | -9m+-10m+7m+12m+2m=-6 | | 1.5×h=1 | | -1/(2(x+4)=-12) | | 49k-8=64 | | 3x-13+45=90 | | 1=1108=5x-5 | | 4=2x-206=160 | | 9z-z-8z+4z=20 | | (x+5)/12=32 | | 2x+2x-2=20 | | 2^x=32^x-16 | | -16w—20w-7w=12 | | 5g-4g-g+4g-3g=4 | | -10k-10=60 | | z/6+9=-26 | | x=32-5*12 | | 3t+10=2 | | -4v+10=22 | | 11r-4r+2r=9 | | 17j-15j-2j+2j=20 | | 10x+20=7x-49 | | 11d-2d-8d+2d-2d=7 | | y=(2500*0.03)^11 | | 2x+5=x+4/5 | | z/6+9=−26 | | 1.27=x(x+.5 | | 6a-9=75 | | 19w-8w-11w+w=16 | | 4x-4=4x-14 | | s=s+60 | | X=-2y+56 |