First term ,a=4 , common difference =4-7=-3, n =50
sum of first 50terms= (50/2)[2×4+(50-1)(-3)]
=25×[8+49]×-3
=25×57×-3
=25× -171
= -42925
derivation of the formula for the sum of n terms
Progression, S
S=a1+a2+a3+a4+...+an
S=a1+(a1+d)+(a1+2d)+(a1+3d)+...+[a1+(n−1)d] → Equation (1)
S=an+an−1+an−2+an−3+...+a1
S=an+(an−d)+(an−2d)+(an−3d)+...+[an−(n−1)d] → Equation (2)
Add Equations (1) and (2)
2S=(a1+an)+(a1+an)+(a1+an)+(a1+an)+...+(a1+an)
2S=n(a1+an)
S=n/2(a1+an)
Substitute an = a1 + (n - 1)d to the above equation, we have
S=n/2{a1+[a1+(n−1)d]}
S=n/2[2a1+(n−1)d]
19/20
19/20 = 0.95
0.9 < 0.95
Answer:
y = -
x + 4
Step-by-step explanation:
The equation of a line in slope- intercept form is
y = mx + b ( m is the slope and c the y- intercept )
Calculate m using the slope formula
m = (y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = (2, 3) and (x₂, y₂ ) = (4, 2) ← 2 points on the line
m =
= - 
Note the line crosses the y- axis at (0, 4) ⇒ c = 4
y = -
x + 4 ← equation of line
Answer:
75+150=225 in^2
Step-by-step explanation:
Separate each layer.
Area1+Area2= Total area
A1= a*b*d
A2=a*c*d
A1=5*5*3=75 in^2
A2=5*10*3=150 in^2
75+150=225 in^2
Answer:
6=65
Step-by-step explanation:
34