Answer:
145/2
Step-by-step explanation:
d=[2x+1-x] = [5x+1 -(2x+1)]
x+1=3x
x-3x=-1
-2x=-1
x=1/2
therefore first term is 1/2
second term is 2(1/2)+1= 2
common difference d is 2-1/2=3/2
sum of first n terms is n/2 [2a+(n-1)d] where n=10
sum of first 10 terms= 10/2[2×1/2+(10-1)3/2]
=5[1+(9)3/2] =5[1+27/2] = 5[29/2] =145/2
Step-by-step explanation:
cot x + 2 tan x + tan³ x
Write in terms of sine and cosine:
(cos x / sin x) + 2 (sin x / cos x) + (sin³ x / cos³ x)
Find the common denominator:
(cos⁴ x / (sin x cos³ x) + 2 (sin² x cos² x / (sin x cos³ x)) + (sin⁴ x / (sin x cos³ x))
Add:
(cos⁴ x + 2 sin² x cos² x + sin⁴ x) / (sin x cos³ x)
Factor:
(sin² x + cos² x)² / (sin x cos³ x)
Pythagorean identity:
1 / (sin x cos³ x)
Multiply top and bottom by cos x:
cos x / (sin x cos⁴ x)
Simplify:
cot x sec⁴ x
Answer:
She started with 26 boxes.
Step-by-step explanation:
She started with x boxes. Then she bought 8 more boxes. Now she had x + 8 boxes. Then half the boxes were destroyed, so she has the other half of the boxes. Half of the boxes is (x + 8)/2. She has now 17 boxes, so (x + 8)/2 = 17.
(x + 8)/2 = 17
Multiply both sides by 2.
x + 8 = 34
Subtract 8 from both sides.
x = 26
She started with 26 boxes.
First we need to know how much each pen costs. So we take 11.77 and divide it by 11. That gives us 1.07 per pen. So answer choice A has 4 pens for 4.44, so we need to multiply 1.07 x 4. That gives you 4.28, so we know that isn't the correct answer. For option B, we need to multiply 1.07 x 5. That is 5.35, so that also can't be the answer. For C, we need to do 1.07 x 6, and that gives us 6.42. So we know the correct answer is option C.
