Question

If l, m, and n are parallel, solve for x. Type in numerical values only, do not type in x=

Answer 1

x = 11

Explanation:

According to proportionality theorem, the transversal is divided proportionally as it cuts across parallel lines l, m, and n.

Therefore:

`(12.8)/(x + 5) = (x - 3)/(10)`

Cross multiply

`(12.8)(10) = (x + 5)(x - 3)`

`128 = x^2 - 3x + 5x - 15`

`128 = x^2 + 2x - 15`

`0 = x^2 + 2x - 15 - 128`

`0 = x^2 + 2x - 143`

Factorise:

`0 = x^2 - 11x + 13x - 143`

`0 = x(x - 11) +13(x - 11)`

`0 = (x - 11)(x + 13)`

x = 11 or x = -13

We'd take the positive value.

Therefore, the value of x is 11.