Here's the question you clicked on:
exox
A laptop computer purchased for $1400. After each year the resale value decreased by 35%. What will be the resale value after 4 years?
Year 1 (35% of 1400= 490) 1400- 490= 910 Year 2 (35% of 910 = 318.5) 910- 318.5= 591.5 Year 3 (35% of 591.5= 207 * rounded to the nearest hundredth*) 591.5- 207= 384.5 Year 4 (35% of 384.5 = 134.6 *rounded to the nearest hundredth* ) 384.5 - 134.6= 249.9.
@flapdragon why do such long calculation you will get same answer as mine unless you haven't made any mistake
Just in case the person who asked the question needs to know how I got the answer. :)
in this case a=1,b=k,c=k+1 so for \[\Delta = k ^{2}-4\left( k +1 \right) =k ^{2}-4k -4\] now use quadratic formula on this to find k.\[\div 2k=\left( 4\pm \sqrt{16-4\times -4} \right)\div2=\left( 4\pm \sqrt{32} \right)\div2=\left( 4\pm4\sqrt{2} \right)\]\[\div2=2\pm2\]