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Marina CMI [18]

3 years ago

11

5r^2-38r-16 i must factor by grouping but im very lost

1 answer:

scoray [572]3 years ago

7 0

So let's take this step by step. The only two numbers that will give you 5 is 1 and 5. The numbers that can give you 16 is 1, 2, 4, 8, 16. The whole idea behind factoring is playing with these numbers and seeing what gives you -38.

Let's set up the factors now:

(5r + __) (r - __)

What two numbers could you put in the blanks? If you multiply everything together, you'll have to get 5r^2-38r-16.

If you play around with the numbers, 2 and 8 could be used. So let's plug them in.

(5r + 2)(r - 8)

If you multiply them out, you'll get 5r^2 - 40r + 2r - 16, or 5r^2 - 38r -16. Hope that helps.

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4 years ago

()) A rectangular piece of paper has a perimeter of 22 inches and an area of 28 square

Natasha2012 [34]

Given:

Perimeter of a rectangular paper = 22 inches.

Area of the rectangular paper = 28 square inches.

To find:

The dimensions of the rectangular paper.

Solution:

Let l be the length and w be the width of the rectangular paper.

Perimeter of a rectangle is:

$P=2(l+w)$

Perimeter of a rectangular paper is 22 inches.

$2(l+w)=22$

$l+w=\dfrac{22}{2}$

$l=11-w$ ...(i)

Area of a rectangle is:

$A=lw$

Area of the rectangular paper is 28 square inches.

$28=lw$

Using (i), we get

$28=(11-w)w$

$28=11w-w^2$

$w^2-11w+28=0$

Splitting the middle term, we get

$w^2-7w-4w+28=0$

$w(w-7)-4(w-7)=0$

$(w-7)(w-4)=0$

Using zero product property, we get

$(w-7)=0\text{ and }(w-4)=0$

$w=7\text{ and }w=4$

If $w=7$ , then by using (i)

$l=11-7$

$l=4$

If $w=4$ , then by using (i)

$l=11-4$

$l=7$

Therefore, the dimensions of the paper are either $7\times 4$ or $4\times 7$ .

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3 years ago

Factorise x2 - 38x + 72

Julli [10]

Answer:

Step-by-step explanation:

x² - 38x + 72 = (x-2)(x-36)

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Answer:

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ohaa [14]

Answer:

On the image.

Step-by-step explanation:

On the image. Hope this helps!

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