The area of a square postage stamp is 81/100 in 2. what is the side length of the stamp?

For how answer my question this will be the last question can you answer in math subject

Combine like terms to make a simpler expression 3z+z

Answer asap ill give ! ’ a sample of radioactive material decays over time. the number of grams, y , of the material remaining x days after the sample is discovered is given by the equation y = 10(0.5)^x. what does the number 10 represents in the equation? a. the half-life of the radioactive material, in days b. the amount of the sample, in grams, that decays each day c. the time, in days, it will take for the samples to decay completely d. the size of the sample, in grams, at the time the material was discovered