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: (x2+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
or x=−3


(1 point)
Karim's first mistake occurs at Step

Answer 1

Step 3.

Explanation: (−3x − 24) factors as −3(x + 8), not +3(x + 8), so the sign is wrong when factoring in Step 3.