How to find the sum of 2+4+6....+40?

Mathematics

1 answer:

grandymaker [24]2 years ago

3 0

Answer 420.
a, is the first term. d is difference.
Since this is an arithmetic progression, I use this formula.
Un = nth term
Sn = sum of terms.
First find the number of terms, which is 20.
Then use the second formula to find the sum.

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(d) A car travels at an average speed of 80 km/h. How far does it travel in: (1) 2 hours? (11) 12 minutes?

zepelin [54]

Answer is (1) 160 km in 2 hours and
(2) 16 miles in 12 minutes.

Step by step.
80 km / 1 hour = x km /2 hours
Cross multiply =
x = 160

The second one requires a little more math. Because we are looking at how far in minutes, we change the rate of 80km in 1 hour to 80 km in 60 minutes.
80 km / 60 = x / 12
Cross multiply
12x = 960
Solve for x by dividing both sides by 12
X = 16

I did the math on a print screen to explain the cross multiply.

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1 year ago

Please help me factor this!! Thanks!

Goryan [66]

We need to find two numbers that multiply to 24 (last coefficient) and add to 10 (middle coefficient). Through trial and error, the two values are 6 and 4

6 + 4 = 10
6*4 = 24

So we can break up the 10ab into 6ab+4ab and then use factor by grouping

a^2 + 10ab + 24b^2
a^2 + 6ab + 4ab + 24b^2
(a^2+6ab) + (4ab+24b^2)
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(a+4b)(a+6b)

Therefore, the original expression factors completely to (a+4b)(a+6b)

5 0

2 years ago

What is the sum of first 6 terms

zvonat [6]

Answer:

182

Step-by-step explanation:

Sum = a(r^n -1) ÷ r - 1

1(-3^6 - 1) ÷ -3 -1

= 182

r = t2 ÷ t1 * since they stated that it is geometric

7 0

1 year ago

What is the value of x, when -25(x - 4) = -55(x - 10)?

Finger [1]

$-25(x - 4) = -55(x - 10)\\\\-25x+100=-55x+550\ \ \ |-100\\\\-25x=-55x+450\ \ \ \ |+55x\\\\30x=450\ \ \ |:30\\\\x=15$

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3 years ago

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lord [1]

All triangles are similar.
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2 years ago