Aidez moi svp c hyper urgent

1) -2x²+23x-30 = 0

b²-4ac = 23²-4(-2*-30) = 23²-4(60) = 529-240 = 289
Δ>0  2solutions

x1 = -b+√Δ/2a = -23+17/-4 = -6/-4 = 3/2
x2 = -b-√Δ/2a )= -23-17/-4 = -40/-4 = 10

b) 20-9² = 4
-9x²+16 = 0

b²-4ac = 16²-4(-9*0) = 16² =256
Δ>0, 2solutions
x1 =-b+VΔ/2a = -16+16/-18 = 0
-x2=b-√Δ/2a = -16-16/18  =-32/18  =-16/9

c) -x²-5 = x²
-2x²-5 = 0

b²-4ac = (-5)²-4(-2*0) = 25
Δ>0 2solutions
x1 -b-√Δ/2a  =  -5+5/-4 = 0
x² = b-√Δ/2a = +5+5/-4 = -10/4 = -5/2

d) x²+9X+25 = x
x²+10x+25 = 0
b²-4ac =  +10²-4(1*25) = 100-100 = 0
Δ=0, 1 solution
-b/2a = -10/2 = -5

je c pas trop on voit pas