Jon's new mini computer monitor has a 20 cm by 24 cm LCD screen with a plastic trim border. The total area of the monitor and border is 672 cm2. How wide is the trim around the monitor?

Question

anonymous · Answer

(20+x)(24+x)=672
x is the width of the border

anonymous · Answer

I got x^2+44x+480=672. What do I do now?

anonymous · Answer

solve
x^2+44x-192=0

anonymous · Answer

How do I solve that?

anonymous · Answer

you can factor
what factors of -192 add up to +44, (one is negative, one is positive)

anonymous · Answer

+4 & -48.

anonymous · Answer

close, +48 and -4

anonymous · Answer

so your factored equation is
(x+48)(x-4)=0

anonymous · Answer

x=-48, 4
because length can't be negative, you discard the -48
the width of the border is 4 cm

anonymous · Answer

you mean, you discard -4 and have a width of 48 cm