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azamat
2 years ago
12

What value of B makes the expression. x² + Bx + 81 a perfect square trinomial?

Mathematics
2 answers:
Lina20 [59]2 years ago
5 0

Answer:

<h2>B. 18</h2>

Step-by-step explanation:

\text{Use}\ (a+b)^2=a^2+2ab+b^2\\\\\text{We have}\ x^2+Bx+81.\\\\\underbrace{x^2+Bx+9^2}_{a^2+2ab+b^2}\to Bx=2(9)x\\\\Bx=18x\to B=18

Oxana [17]2 years ago
4 0

Answer:

B.) 18

Step-by-step explanation:

To find the correct b value we use this formula

b² - 4ac = 0

b = What we are solving for

a = 1

c = 81

b² - 4(1)(81) = 0

b² - 324 = 0

b² = 324

b = \sqrt{324}

b = ±18

And 18 is one of the answer choices

So B.) 18 is the correct answer.

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Put the amount you go up or down on the Y-axis over how much you go right or the x-axis

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8 0
3 years ago
Find the 59th term of the following arithmetic sequence. 15, 23, 31, 39
m_a_m_a [10]

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4 0
2 years ago
Working together, it takes Sam, Jenna, and Francisco two hours to paint one room. When Sam works alone, he can paint one room in
lutik1710 [3]

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Step-by-step explanation:

Given : Working together, it takes Sam, Jenna, and Francisco two hours to paint one room.

When Sam works alone, he can paint one room in 6 hours. When Jenna works alone, she can paint one room in 4 hours.

Let 't' be the time taken by Francisco to paint one room on his own.

Then , we have

Rate of work of  Sam +Rate of work of Jenna + Rate of work of  Francisco =Rate of work they all do together

\dfrac{1}{6}+\dfrac{1}{4}+\dfrac{1}{t}=\dfrac{1}{2}

i.e.  \dfrac{1}{t}=\dfrac{1}{2}-(\dfrac{1}{6}+\dfrac{1}{4})

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i.e.  \dfrac{1}{t}=\dfrac{1}{2}-\dfrac{10}{24}

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i.e. t= 12

Hence,  Francisco would take 12 hours to  paint one room on his own.

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