8.1.1: 2--it should be 40 months
#55 from 8.2.1 is still missing
63--good explanation/justification! :)
66: c--try using Giant Ones on problems like this, like you did in part a and the second way you did part d. see attached photo.
67.b: you have the correct work, but didn't finish to give an answer to the question: How many hours?
12 in (1/2 hr/in)= 6 hours
70--much better!
8.2.3 (a): 72--Beautiful! Great work on parts a-d! e: 1/6^3, f: anything over itself = ? (1, not 0)
73.d. there should only be one 5, then go ahead and multiply/simplify the constants: 4^2*5=80x^4
78--both of them are correct
79: take another look at this one-- 10^-2=1/100
88.a. the exponent on 10 should be -1
b. this one is tricky-- 0.83 x 100^2 = 0.83 x 10^4 = 8.3 x 10^5
91.e. try this one again, remember to use correct order of operations--multiply before addition or subtraction.
8.2.3 (b): 83: negative exponents don't make the base negative--they just move to the denominator.
simplify/rewrite a and b. ex: c = 10
84: Read the directions and try this one again. Also, how did the 6s and 10s turn into 2s?
see attached picture, I did a as an example
95. b. should be 10^-1, not -10
c. look at the picture I attached for 66.c and try this one again.
d. need to fix this one. Remember, anything over itself = 1
8.2.4: 101. b. Nice! Thumbs up!
102-104: great work! But, remember when you're working on future problems with scientific notation to use what you know about exponents to make the work simpler.
ex: (1.75 x 10^20)(6.01 x 10^14) = 1.75 x 6.01 x 10^20 x 10^14 = 10.5175 x 10^34
= 1.05175 x 10^35
104: Add Mercury, Venus, and Earth--they all have the same exponent, which means they all have the same number of place values, so you get 21.81 x 10^7 = 2.181 x 10^8 + Mars = 3.597 X 10^8
109: answers should be in scientific notation: ex: a. (3 x 10^2)(2 x 10^3) = 3 x 2 x 10^2 x 10^3 =
6 x 10^5 need to fix b and c