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]
(3x²+6x+9)(8x-4)= 24x³-12x²+48x²-24x+72x-36= 24x³+36x²+48x-36
R: E
Answer:
The slope is -2
Step-by-step explanation:
m =
y2 - y1
x2 - x1
that's the formula
Answer:
21
Step-by-step explanation:
PEMDAS:
Parenthesis
Exponent
Multiplication and Division
Addition and Subtraction
21-3+3
18+3
21
Hope this helps!
Answer:
Slope: -5 Y-intercept: 3
Step-by-step explanation:
the slope intercept of a linear equation is:
y=mx+b
were m is slope. and b is the y intercept
therfore the problem is:
y=-5x+3
m=-5 so the slope is -5
b=3 so the y-intrercept is 3
