Answer:
The sum of the age of pupils is 81
Step-by-step explanation:
Let sum of age of 18pupils = x
Average ages = 4.5
Average = total/no. of pupil
4.5 = x/18
x = 81
2040 = n/2(20+(n-1)4)
4080 = n(20+4n-4)
4080= 20n +4n^2 -4n
1020 = 4n + n^2
n^2 +4n -1020 =0
use common formula (can't write out so just look at answers. sorry)
which gives answers of n=-34 and n=30. since n can only be positive, n=30 so there are 30 rows. I liked that challenge
Answer:
x = ± 2, x = 3
Step-by-step explanation:
note that x = 2 gives
2³ - 3(2)² - 4(2) + 12 = 8 - 12 - 8 + 12 = 0
Hence x = 2 is a root and (x - 2) is a factor
x³ - 3x² - 4x + 12 ÷ (x - 2)
= (x - 2)(x² - x - 6)
= (x - 2)(x + 2)(x - 3), hence
(x - 2)(x + 2)(x - 3) = 0
equate each factor to zero and solve for x
x - 2 = 0 ⇒ x = 2
x + 2 = 0 ⇒ x = - 2
x - 3 = 0 ⇒ x = 3
Answer:
The answer is 1.
Step-by-step explanation:
Nobel gases have full shell of valence electrons, that is why they tend to not enter any chemical reactions because they are satisfied while metals have very few electrons in the valence shell, so they are active in any chemical reaction.
