x^2 + 4x ???

Question

give u a rectangle

width is x
length is x+4

area is 60

find x???

isn't it x(x+4) = 60
x^2 + 4x = 60
then what do I do?

I'm not good at math and english....

thanks you. You're so nice ^_^

Answer 1

From that point you need to factor the equation to solve or use the quadratic equation. This one is easy enough to factor.
Rewrite in the form of ax^2 + bx + c = 0, then factor.
x^2 + 4x - 60 = 0,
(x+10)(x-6)=0,
x=-10 and 6, since -10 doesn't work for a length, n=6.
width=6 and length = 6+4=10
Always double check your answer.

Answer 2

first subtract 60 from both sides
x^2 + 4x -60 = 0
then you have to either factor it or use the quadratic eqn
this has a nice even factor so we'll do that
(x-6)(x+10) = 0

so x = 6 and x = -10

since x is a length it must be positive so x = 6

Answer 3

X^2+4x-60=0
(x-6)(x+10)=0
x=6 and x=-10

Since this is a rectangle the only logical answer is x=6