Mathematics

Question

QUESTION FOR 50 POINTS
Solve this equation using an algebraic method: (x + 4)(x - 4) = 9
Choices are:
x=5
x=4 and x=-4
x=9
x=5 and x=-5

2 Answer

  • (x+4)(x-4)=9  expand left side by performing indicated multiplication...

    x^2-16=9 add 16 to both sides

    x^2=25  take the square root of both sides...

    x=±5

    x=-5 and 5

    So the answer would be the bottom choice.
  • the answer is 
    x=5 and x=-5
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