Factor the polynomial. 13x² – 20x – 12

Mathematics

1 answer:

erma4kov [3.2K]2 years ago

6 0

Answer:

(13 x + 6) (x - 2)

Step-by-step explanation:

Factor the following:

13 x^2 - 20 x - 12

Factor the quadratic 13 x^2 - 20 x - 12. The coefficient of x^2 is 13 and the constant term is -12. The product of 13 and -12 is -156. The factors of -156 which sum to -20 are 6 and -26. So 13 x^2 - 20 x - 12 = 13 x^2 - 26 x + 6 x - 12 = x (13 x + 6) - 2 (13 x + 6):

x (13 x + 6) - 2 (13 x + 6)

Factor 13 x + 6 from x (13 x + 6) - 2 (13 x + 6):

Answer: (13 x + 6) (x - 2)

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The average heights of x number of girls and 15 boys is 123. if the average heights of boys is 125 and that of girls is 120.find

mamaluj [8]

Answer:

$x = 10$ . In other words, there number of girls is $10$ .

Step-by-step explanation:

The average of a number of measurements is equal to the sum of these measurements over the number of measurements.

$\displaystyle \text{Average} = \frac{\text{Sum of measurements}}{\text{Number of measurements}}$ .

Rewrite to obtain:

$\begin{aligned}& \text{Sum of measurements}= (\text{Number of measurements}) \times (\text{Average}) \end{aligned}$ .

For this question:

$\begin{aligned}& \text{Sum of heights of boys} \\ &= (\text{Number of boys}) \times (\text{Average height of boys}) \\ &= 15 \times 125 = 1875\end{aligned}$ .

$\begin{aligned}& \text{Sum of heights of girls} \\ &= (\text{Number of girls}) \times (\text{Average height of girls}) \\ &= x \times 120 = 120\, x\end{aligned}$ .

Therefore:

$\begin{aligned}& \text{Sum of boys and girls} \\ &= \text{Sum of heights of boys} + \text{Sum of heights of girls}\\ &= 1875 + 120\, x\end{aligned}$ .

On the other hand, there are $(15 + x)$ boys and girls in total. Using the formula for average:

$\begin{aligned}& \text{Average height of boys and girls} \\ &= \frac{\text{Sum of heights of boys and girls}}{\text{Number of boys and girls}} \\ &= \frac{1875 + 120\, x}{15 + x}\end{aligned}$ .