A square of side 5 is removed from a square of side 12. How will the remaining area be written using the (a−b)(a+b) model?

Correct answer: 7 × 17

Direct answer: Option A, 7 × 17, is correct. The large square has area 12² and the removed square has area 5². Therefore, the remaining area is 12² − 5². The difference-of-squares identity says a² − b² = (a − b)(a + b). Substituting a = 12 and b = 5 gives (12 − 5)(12 + 5) = 7 × 17. Option A follows exactly. Option B multiplies the two given side lengths, but that does not represent the difference between their square areas. Option C uses 12 instead of the difference 12 − 5. Option D uses 5 instead of the required sum 12 + 5. A check confirms that 144 − 25 = 119 and 7 × 17 = 119. Memory cue: difference of squares means difference times sum.