Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**unique****Member**- Registered: 2006-10-04
- Posts: 419

Find the distance between the point (3,1) and the line y = x - 4

i did like this :

y = -2x + b < equation

1 = -2(2) + b < use (3,1)

1 = -6 + b < add 6

7 = b

y = -2x + 7 < completed equation

THAN

x - 4 = -2x + 7 < substitution

add 4 both sides

x = -2 + 11

3x = -2 + 11

3x = 9

x = 9/3 < solved for x

THAN

y = -2 (9/3) + 7

y = -6 + 7

y = 1 < solved for y

THAN distance formula

D = sqrt( ( (x2 - x1)^2 + (y2 - y1)^2 )

(3,1) and (3,1)

D = sqrt ( (3 - 3)^2 + (1 - 1)^2 )

D = sqrt( 0 + 0)

D = 0 < solved

answer is zero

correct?

Desi

Raat Key Rani !

Offline

**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

.

.

. /

o . /

o. /

o /

.o /

. o /

. . /

....o...........

. / o

. / o

./ o

/ o

. o

. o

.

. square root of 2

. one down and one right.

**igloo** **myrtilles** **fourmis**

Offline

**unique****Member**- Registered: 2006-10-04
- Posts: 419

so am i right?

Desi

Raat Key Rani !

Offline

**Monox D. I-Fly****Member**- From: Indonesia
- Registered: 2015-12-02
- Posts: 1,159

No. The distance of a point and a line is 0 if the point is in the line. In your question, however, the coordinate (3,1) doesn't satisfy the equation y = x - 4 because 3 - 4 ≠ 1.

Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away. May his adventurous soul rest in peace at heaven.

Offline

**Mathegocart****Member**- Registered: 2012-04-29
- Posts: 1,910

Problem solved, after 10 years..

The integral of hope is reality.

May bobbym have a wonderful time in the pearly gates of heaven.

He will be sorely missed.

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

Hi;

John gave an answer in post #2 also.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline

**Monox D. I-Fly****Member**- From: Indonesia
- Registered: 2015-12-02
- Posts: 1,159

Well, I answered post #3, since he seemed to not understand implicit answers.

Actually I never watch Star Wars and not interested in it anyway, but I choose a Yoda card as my avatar in honor of our great friend bobbym who has passed away. May his adventurous soul rest in peace at heaven.

Offline

**bobbym****bumpkin**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606

No problem.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline