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azamat
3 years ago
12

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

Mathematics
2 answers:
Lina20 [59]3 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]3 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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