A student was asked to find mZA and mZB given that mZD = 112°,
mZA = (9x – 20)°, and mZB = (9x – 12). She
incorrectly said mZA = 30° and mZB = 38°. Find
mZA and mZB. What mistake might the student
have made?

we don't have enough info to solve this

20%

step-by-step explanation:

let's call the solutions x₁ = (5 - 2√7)/3 and x₂ = (5 + 2√7)/3

then the equation is (x-x₁)(x-x₂) = 0

if you fill that in you get a lot of numbers which you can recognize as ax²+bx+c=0.

step-by-step explanation:

you can see that a=1 (there is just an x²)

b = (-5 -2√7 + 2√7 - 5)/3 = -10/3

c = -2√7)/3 ) * (-5+2√7)/3) = -1/3

so your answer is 3x^2 – 10x – 1 = 0