Answer:
(3w - 7)(3w + 7)
Step-by-step explanation:
The expression is a difference of squares and factors in general as
a² - b² = (a - b)(a + b)
Thus
9w² - 49
= (3w)² - 7²
= (3w - 7)(3w + 7)
Answer:
Step-by-step explanation:
ten students are chosen from a statistics class of 300 let x be the number who got an a in the class
I think the answer will be certain
Answer:
It will take Sarah 2 1/2 hours to mow 10 lawns
It will take Sarah 1 2/3 hours to clean 10 pools
Step-by-step explanation:
During the summer holidays, Sarah earns pocket money by mowing the lawn. She can mow 6 lawns in 1 1/2 hour and clean a pool in one-sixth of an hour. How long does Sarah take to clean 10 pools and 10 lawns?
Number of lawns : Time to mow lawns = 6 : 1 1/2
= 6 : 3/2
Number of lawns : Time to mow lawns = 10 : x
6 : 3/2 = 10 : x
6 ÷ 3/2 = 10/x
6 * 2/3 = 10/x
12/3 = 10/x
Cross product
12 * x = 3 * 10
12x = 30
x = 30/12
x = 2 6/12
x = 2 1/2 hours
It will take Sarah 2 1/2 hours to mow 10 lawns
Number of pools cleaned : time taken = 1 : 1/6
Number of pools cleaned : time taken = 10 : x
1 : 1/6 = 10 : x
1 ÷ 1/6 = 10/x
1 * 6/1 = 10/x
6 = 10/x
Cross product
6 * x = 10
6x = 10
x = 10/6
x = 1 4/6
x = 1 2/3 hours
It will take Sarah 1 2/3 hours to clean 10 pools
Answer:
19.93 moles
Step-by-step explanation:
