Answer:
Step-by-step explanation:
hello :
5x²+8x-4 quadratic expression when : a = 5 and b=8 and c= -4
∆ = b²-4ac ∆ = 8²-4(5)(-4) = 64 +80 = 144 = 12²
X1 = ( -b -√∆)/2a X1 = (-8-12)/10 = -20/10= -2
X2 =(-b+√∆)/2a X2 = (-8+12)/10 = 4/10 = 2/5
us factorisation : a(X-X1)(X-X2)
5x²+8x-4= 5(x+2)(x-2/5) = (x+2)(5x-2)
you can verify ; (x+2)(5x-2) = 5x²-2x+10x-4 = 5x²+8x-4
