
Lilly N.
asked 05/24/22OMG I BEG PLS SOMEONE HELP ME
What is the discriminant and number of real solutions of -8x2 + 9x - 4 = 0
1 Expert Answer
Raymond B. answered 05/24/22
Math, microeconomics or criminal justice
-8x^2 + 9x - 4 = 0
the discriminant is b^2 -4ac = 9^2 -4(-8)(-4) = 81-128 =- 47 <0
if the discriminant is less than zero there are no real solutions
8x^2 -9x +4 = 0
x = 18/16 + or - (1/16)sqr(81-128)
x= 9/8 + or - (i/16)sqr47
there are two imaginary solutions
if you used descartes' rule of signs, that would show a potential maximum two positive real solutions, either 0,1, or 2, but that's consistent with zero real solutions. 0<2.
rule of signs shows zero possible negative real solutions
by deduction just on rule of signs there are either 2 real positive solutions or 2 imaginary solutions.
Answer turns out: 2 imaginary solutions, just by looking at the discriminant.
discriminant is b^2 -4ac where y=ax^2 +bx + c
a = -8, b=9, c= -4
b^2 -4ac = 9^2-4(-8)(-4) = 81-128 = -47<0
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Barry D.
05/29/22