Answer:
Original expression: [tex]3x^2+8x-16[/tex]
Let [tex]a[/tex] be the quantity Amir subtracted from the original expression.
Expression after subtraction: [tex]x^2-4[/tex]
[tex]\implies (3x^2+8x-16)-a=x^2-4[/tex]
Solve for [tex]a[/tex]:
[tex]\implies 3x^2+8x-16-a=x^2-4[/tex]
Add 4 to both sides:
[tex]\implies 3x^2+8x-12-a=x^2[/tex]
Subtract [tex]x^2[/tex] from both sides:
[tex]\implies 2x^2+8x-12-a=0[/tex]
Add [tex]a[/tex] to both sides:
[tex]\implies 2x^2+8x-12=a[/tex]
Therefore, Amir subtracted [tex]2x^2+8x-12[/tex] from the original expression.
