the length of a rectangle is 4 meters less than twice its width. The area of the rectangle is 70m2. Find the dimensions of the rectangle

Question

freshavacado850 · Answer

off topic but your pfp is hot

5lim3Ty · Answer

@freshavacado850 wrote:

off topic but your pfp is hot

lmao

Bxmp · Answer

Area=Length x Width.
Length is 2w-4.
So, 
$$70=w(2w-4)$$
$$70=2w^2-4w$$
$$2w^2-4w-70=0$$
Factor the equation:
$$2(w-7)(w+5)=0$$
Can you continue from here?

Joe348 · Answer

2w-14 times w+5?

Bxmp · Answer

No, 
$$w-7=0$$
Add 7 to each side.
$$w=7$$
So, correct, it is 7 your width.

freshavacado850 · Answer

If the width = x m then the length =  2x - 4 m

Area =  x(2x - 4) = 70

2x^2 - 4x - 70 = 0

2x^2 - 14x + 10x - 70 = 0

2x(x - 7) + 10(x - 7) = 0

(2x + 10)(x - 7) = 0
x = 7 or -5  ( ignore negative)
width = 7 m and length = 10 m  answer

Bxmp · Answer

Are you following so far?

Bxmp · Answer

@freshavacado850 wrote:

If the width = x m then the length = 2x - 4 m Area = x(2x - 4) = 70 2x^2 - 4x - 70 = 0 2x^2 - 14x + 10x - 70 = 0 *2x(x - 7) + 10(x - 7) = 0* Wrong. (2x + 10)(x - 7) = 0 x = 7 or -5 ( ignore negative) width = 7 m and length = 10 m answer

Joe348 · Answer

trying to but not understanding

Joe348 · Answer

brb

Bxmp · Answer

@bxmp wrote:

@freshavacado850 wrote:

If the width = x m then the length = 2x - 4 m Area = x(2x - 4) = 70 2x^2 - 4x - 70 = 0 2x^2 - 14x + 10x - 70 = 0 *2x(x - 7) + 10(x - 7) = 0* Wrong. (2x + 10)(x - 7) = 0 x = 7 or -5 ( ignore negative) width = 7 m and length = 10 m answer

And how did you get 10?, never showed any work for that.

Joe348 · Answer

where you get -7 from though?

Bxmp · Answer

It's a positive seven, and from right here.

@bxmp wrote:

No, $$w-7=0$$ Add 7 to each side. $$w=7$$ So, correct, it is 7 your width.

freshavacado850 · Answer

@freshavacado850 wrote:

If the width = x m then the length = 2x - 4 m Area = x(2x - 4) = 70 2x^2 - 4x - 70 = 0 2x^2 - 14x + 10x - 70 = 0 2x(x - 7) + 10(x - 7) = 0 (2x + 10)(x - 7) = 0 x = 7 or -5 ( ignore negative) width = 7 m and length = 10 m answer

I got this from google also

Bxmp · Answer

$$(w-7)\rightarrow(w-7=0)\rightarrow(w=7)$$

Bxmp · Answer

Do you know how to get x-intercepts from the quadratic formula?