The triangle inequality tells us that the sum of the two shorter sides of a triangle must be greater than the third side.
Here, 21 cm is one of the shorter sides, and x cm must be the length of the other shorter side.
So using the triangle inequality, 21+x > 2x or x<21 cm To the nearest 0.1 cm, the greatest possible length of the longest side (2x) is 2*21-0.1 cm = 41.9 cm < 2x=42 cm.
You need to solve 10^6 * 10^2 without using standard notation. As with variables, if you had x^6 * x^2 you would add the exponents. Replace x with 10. Your answer is 10^8. As a sidenote, only multiply exponents when raising a power to another power, e.g. (10^6)^2 = 10^12.
