Triangle inequality proof
/a + b/ ≤ /a/ + /b/

a^2+b^2+2|a||b|≥a2+b2+2ab(|a|+|b|)2≥|a+b|2(∵∀x∈R;x2=|x|2)∴|a|+|b|≥|a+b|\

Step-by-step explanation:

For this case we have the following expression:
 24 + 56
 The factors of the numbers are:
 24: 1, 2, 3, 4, 6, 8, 12, 24
 56: 1, 2, 4, 7, 8, 14, 28, 56
 So, factoring we have:
 24 + 56 = 8 (3 + 7)
 Simone wrote:
 24 + 56 = 8 (4 + 7)
 Therefore his error is:
 Simone did not use the correct factors for 24 in the equation
 
 Simone did not use the correct factors for 24 in the equation