Seems to be an arythmetic sequence
Sn=[n(a1+an)]/2
where
Sn means sum of all terms up the nth term
n=number of terms
a1=first term
an=nth term
so from 86 to the 22th term is from a1 to a22
find teh sequence
miknus 7 each time
an=a1+d(n-1)
an=87-7(n-1)
find 22n term
a22=87-7(22-1)
a22=87-7(21)
a22=87-147
a22=-60
S22=[22(87-60)]/2
S22=[22(27)]/2
S22=594/2
S22=297
the sum is 297
He must get a 65 as a minimum grade on his third test to get an average of 70.
Equation is
85 + 60 + x
------------------- greater than or equal to 70
3
Y= f(x)= ax+b
when x= -1, y= -1
-1= -a+b | * ( -1)
when x= -3, y=2
2= -3a+b
-3a+b= 2
a - b= 1
--------------
2a=3
a=3/2 is the slope
25d^2-30d-35d+42=25d^2-65d+42.
Which question do u need help with
