Hello,
We have : (a + b)² = a² + 2ab + b²
4x² + 20x + 25 = (2x)² + 2 × 2x × 5 + 5² = (2x + 5)² → answer B
Here, we have a = 2x and b = 5 !
Answer:
r = 4/5
Step-by-step explanation:
Formula
Sum of an infinite geometric series = a / (1 - r)
Givens
Sum = 5*a
a = a
r = ?
Solution
5a = a/(1 - r) Divide both sides by a
5a/a = a / (a * (1 - r) The a's on the right cancel
5 = 1 / (1 - r) Multiply both sides by 1 - r
5*(1 - r) = 1*(1 - r)/(1 - r) The 1 - r s on the right cancel
5*(1 - r) = 1 Remove the brackets.
5 - 5r = 1 Subtract 5 from both sides
5-5 - 5r = 1 - 5 Combine
-5r = - 4 Divide by - 5
r = 4/5
Answer:
18
Step-by-step explanation:
The LCM is 18.
9x2=18
2x9=18
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