Question

Karim is solving the quadratic equation x^2 + 5x - 24 = 0 by grouping. His work is shown below.
Determine the first step at which Karim makes an error.
Step 1:x^2 + 8x + (-3x)- 24=0
Step 2: (x^2+ 8x) +(-3x-24) =0
Step 3:x(x+8) + 3(x + 8)= 0
Step 4: (x+8)(x+3)= 0
Step 5: x + 8 = 0 or x +3 = 0
x=-8 orx =-3
(1 point)
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Karim's first mistake occurs at Step

Answer 1

Step 3.

Reason: From (-3x - 24) you must factor out -3 to get -3(x + 8), not +3(x + 8). The correct factorization is x(x+8) - 3(x+8) = (x+8)(x-3).