The correct answer is: [A]: " x = 6 " or " x = - 9 " .
________________________________________________________
Explanation:
________________________________________________________
Given the following equation:
________________________________________________________
" x² + 3x – 54 = 0 " ; Solve for "x" ;
_____________________________________________________
Check if the part of the equation on the "left-hand side" can be "factored":
" x² + 3x – 54 " ;
→ We see the " + 3x " and the " – 54 "
Factors of " -54 " that add up to " +3" ;
Let us try: " -9, 6" ; → " -9 + 6 = -3 " ; → " -3 ≠ +3 ;
Let us try: " 9, -6" ; → " 9 + (-6) = 9 – 6 = 3 " ; YES!
→ {that is: " +9 , -6 "} ;
So, we can rewrite the entire equation:
→ " (x + 9)(x – 6) = 0 " ;
→ " x = -9 " ; or, " x = 6 " ; which is:
→ Answer choice: [A]: " x = 6 " or " x = - 9 " .
______________________________________________________
