Question #61e9a

2 Answers
May 1, 2017

x=3,-5

Explanation:

By Pythagoras, we have:

AB^2 = (x-(-1))^2 + (7-4)^2

And so:

5^2 = (x+1)^2 + 3^2
:. 25 = x^2+2x+1+9
:. x^2+2x-15=0
:. (x+5)(x-3)=0

Leading to the two possible solutions:

x=3,-5

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May 1, 2017

x = 3 or -5

Explanation:

Find the distance between A and B in terms of x and equate it to 5.

To do that, we use Pythagoras' Theorem.

(x-(-1))^2 + (7-4)^2 = 5^2
(x+1)^2 + 9 = 25
(x+1)^2 = 16
(x+1) = +- 4
x = 3 or -5