Complete the square to the problem X^2+6x-16=0

Mathematics

1 answer:

marishachu [46]3 years ago

3 0

Answer:

Step-by-step explanation:

$(a+b)^2=a^2+2ab+b^2\qquad(*)\\\\-------------------------------\\\\x^2+6x-16=0\qquad\text{add 16 to both sides}\\\\x^2+6x=16\\\\x^2+2(x)(3)=16\qquad\text{add}\ 3^2\ \text{to both sides}\\\\\underbrace{x^2+2(x)(3)+3^2}_{(*)}=16+3^2\\\\(x+3)^2=16+9\\\\(x+3)^2=25\Rightarrow x+3=\pm\sqrt{25}\\\\x+3=-5\ \vee\ x+3=5\qquad\text{subtract 3 from both sides}\\\\\boxed{x=-8\ \vee\ x=2}$

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Paul can install a 300 hundred square foot hardwood floor in 18 hours. Matt can install the same floor in 22 hours. How long wou

Vadim26 [7]

ANSWER

Paul and Matt will take
$9.9 \: \: hours$
to install the floor working together.

EXPLANATION

First, calculate Paul's rate, which is

$= \frac{1}{18}$

Next, calculate Matt's rate, which is,
$= \frac{1}{22}$

Let us assume that, Paul and Matt took
$x \: hours$
to do the work together.

Then, the rate of working together is,

$= \frac{1}{x}$

Now, add the individual rates and equate to the rate of working together to form an equation that will help us solve for x.

$\frac{1}{18} + \frac{1}{22} = \frac{1}{x}$

Simplify the left hand side

$\frac{11 + 9}{198} = \frac{1}{x}$

$\frac{20}{198} = \frac{1}{x}$

We reciprocate both sides to get (You could have also done cross multiplication).

$\frac{198}{20} = \frac{x}{1}$

$x = 9.9 \: hours$