Question

(x² − 3x)² − 8(x² − 3x) − 20

Answer 1

Step-by-step explanation:

LET (X²-3X) BE A

A²-8A-20

A²-10A+2A-20

A(A-10)+2(A-10)

(A+2)(A-10)

(X²-3x+2)(x²-3x-10)

Answer 2

Answer

Y= 10   OR   Y= -2

Step-by-step explanation:

Let (x^2 - 3x) = Y

⇒Y^2 - 8Y - 20 = 0

using the formula method ; $Y=(-b +/- \sqrt{b^2-4ac})/2a$

a=1 , b= -8 , c= -20

$b^2-4ac$ = Δ(delta)

∴Δ= (-8)^2- 4(1)(-20)

    =64 + 80

  Δ= 144

⇒ Y= [-(-8) + √144]/2      OR      Y=[-(8) - √144]/2

⇒ Y=(8+12)/2      OR     Y=(8 - 12)/2

⇒ Y=20/2    OR    Y= -4/2

⇒ Y=10    OR    Y= -2