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]
Answer:
1.) mean
2.) H0 : μ = 64
3.) 0.0028
4) Yes
Step-by-step explanation:
Null hypothesis ; H0 : μ = 64
Alternative hypothesis ; H1 : μ < 64
From the data Given :
70; 45; 55; 60; 65; 55; 55; 60; 50; 55
Using calculator :
Xbar = 57
Sample size, n = 10
Standard deviation, s = 7.14
Test statistic :
(xbar - μ) ÷ s/sqrt(n)
(57 - 64) ÷ 8 / sqrt(10)
Test statistic = - 2.77
Pvalue = (Z < - 2.77) = 0.0028 ( Z probability calculator)
α = 10% = 0.1
Reject H0 ; if P < α
Here,
P < α ; Hence, we reject the null
Here you go, hope I helped.
Answer:
h=(c/25)-4
Step-by-step explanation:
c-100 = 25h. "/25"
(c/25)-4 = h
<u>Zeros of the function</u>
f(x) = (x + 2)² - 25
f(x) = (x + 2)(x + 2) - 25
f(x) = x(x + 2) + 2(x + 2) - 25
f(x) = x(x) + x(2) + 2(x) + 2(2) - 25
f(x) = x² + 2x + 2x + 4 - 25
f(x) = x² + 4x + 4 - 25
f(x) = x² + 4x - 21
x² + 4x - 21 = 0
x = <u>-(4) +/- √((4)² - 4(1)(-21))</u>
2(1)
x = <u>-4 +/- √(16 + 84)</u>
2
x = <u>-4 +/- √(100)
</u> 2<u>
</u>x = <u>-4 +/- 10
</u> 2<u>
</u>x = -2 <u>+</u> 5<u>
</u>x = -2 + 5 x = -2 - 5
x = 3 x = -7
f(x) = x² + 4x - 21
f(3) = (3)² + 4(3) - 21
f(3) = 9 + 12 - 21
f(3) = 21 - 21
f(3) = 0
(x, f(x)) = (3, 0)
or
f(x) = x² + 4x - 21
f(-7) = (-7)² + 4(-7) - 21
f(-7) = 49 - 28 - 21
f(-7) = 21 - 21
f(-7) = 0
(x, f(x)) = (-7, 0)
<u>Vertex</u>
<u>X - Intercept</u>
<u />-b/2a = -(4)/2(1) = -4/2 = -2
<u>Y - Intercept</u>
y = x² + 4x - 21
y = (-2)² + 4(-2) - 21
y = 4 - 8 - 21
y = -4 - 21
y = -25
(x, y) = (-2, -25)
<u />
