What substitution should be used to rewrite 4x^4-21x^2+20=0 as a quadratic function?

Me solve this problem, and someone clearly explain to me how to solve it.1.) use the value of the discriminant to determine if the given trinomials has 2 real solutions, 1 real solution, or no real solutions. a.  x2  − 4x  − 7 = 0b. 4r2  + 11r  − 3 = 0c. 3m2  + 7 = 0d.  t2  + 2t  + 1 = 0

Which of the choices shown could be used to prove that aacp=abcp ?

∆red ≅ ∆ by rule will give brainiest if possible