Determine the defined range k=0
move expression to the left side and change its sign so it would be the problem = 0
write all numerators above the least common denominator 6k (*2*)-Squared
calculate the sum or the difference
check the solution in the defined range
hope this helped you
Coolio
lw=1000
lets assume that the aluminum sides are the legnth
2 sides
2*15=30
30l=cost of aluminum
steel=10w
wood=(w-10)5=5w-50
we can eliminate the w by solving for w in first relation
lw=1000
divide both sides by l
w=1000/l
sub that for w
10(1000/l)=steel
5(1000/l)-50=wood
wood cost+steel+aluminum cost=total cost
10(1000/l)+5(1000/l)-50+30l=1525
(10000/l)+(5000/l)-50+30l=1525
(15000/l)-50+30l=1525
add 50 to both sides
(15000/l)+30l=1575
times both sides by l
15000+30l²=1575l
minus 1575l from both sides
30l²-1575l+15000=0
factor
(15)(l-40)(2l-25)=0
set each equal to 0
l-40=0
l=40
2l-25=0
2l=25
l=12.5
the there are 2 possible combinations
aluminum=40yd and steel=25yd or
aluminum=12.5yd and steel=80ft
both yield 1000yd² and cost $1525