Answer:
a) 820
b)450
c) -540
d) -294
e) 1440
f) 1425
Step-by-step explanation:
a) it is an arithmetic progression with ratio=4
a1=3,
a2=3+r=3+4=7.....
a20=a1+19r
so a20=3+19*4=3+76=79
S=(a1+an)*n/2 where n=20
so S=(3+79)*20/2=820
b) a15=a1+14*r=2+14*4=2+56=58
S=(a1+a15)*15/2=(2+58)*15/2=60*15/2=30*15=450
It is the same formula for all the exercises
S=(a1+an)*n/2 , where n is the number of terms
c) a40=30+39*(-3)=30-87=-57
So S=(30-57)*40/2=-540
d) a14=5+13*(-4)=5-52=-47
S=(5-47)*14/2=-42*14/2=-42*7=-294
e) it is 5+7+9+......+75
nr of terms = (an-a1) :r+1=(75-5):2+1=36
S=(5+75)*36/2=36*40=1440
f) ratio=7-4=3
the same formula for n= (91-4):3+1=87:3+1=29+1=30
S=(4+91)*30/2=95*30/2=2850/2=1425
Answer:
The percentage maybe went up because of air pollution, and global warming
Step-by-step explanation:
For the answer to the question above, the constant is called the coefficient of proportionality orproportionality constant. If one variable is always the product of the other and a constant, the two are said to be directly proportional. x and y are directly proportional if the ratio yx is constant<span>.
the answer is 1.1</span>
Answer:
Confusing but I got the width is either 12 or 20
12 × 20 = 240 = area check
64 = perimeter = 12 + 12 + 20 + 20 = check
it does not give specifics on what is length so it's one of the 2 which ever one is the width the other is length
