Answer:
60cm^2
Step-by-step explanation:
15 times 8 = 120
divided by 2 = 60
<span>dA/dx = 100 - 4x & the 2nd derivative is -4 [i.e. -ve]
so setting dA/dx to zero will give a maxima
100 - 4x = 0
so x = 25 m
in other words, a rectangle with a given perimeter has the maximum area when it is a square</span>
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<h3>
Answer: 5 - 4i (choice A)</h3>
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Work Shown:
x = the other number
(5+4i)*x = 41
x = 41/(5+4i)
x = 41*(5-4i)/( (5+4i)*(5-4i) ) ..... see note below
x = 41*(5-4i)/( 41 )
x = (41/41)*(5-4i)
x = 5 - 4i
As a way to check, (5+4i)*(5-4i) = 5^2+4^2 = 25+16 = 41
The rule used is (a-bi)(a+bi) = a^2 + b^2
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Note: I multiplied top and bottom by (5-4i) to get rid of the imaginary term in the denominator.
You cannot solve for x but you can factor
to solve in ax^2+bx+c form you must find
b=x+y
a times c=x times y
so solve
3 times 3=9
what 2 number multily to get 9 and add to get 10
9=x times y
the numbers are 9 and 1 so
3x^2+1x+9x+3
(3x^2+1x)+(9x+3)
factor
(x)(3x+1)+(3)(3x+1)
reverse distribute
ab+ac=a(b+c)
(x)(3x+1)+(3)(3x+1)=(x+3)(3x+1)
factored out form is (x+3)(3x+1)