Answer:
f(x) = -60 is your answer
Step-by-step explanation:
Plug in 3 for x
f(x) = 5x² - 7(4x + 3)
f(x) = 5(3²) - 7(4(3) + 3)
Follow PEMDAS. First, solve the parenthesis
3² = 9
4(3) + 3 = 12 + 3 = 15
f(x) = 5(9) - 7(15)
Multiply
f(x) = 45 - 105
Simplify. Subtract
f(x) = 45 - 105
f(x) = -60
f(x) = -60 is your answer
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<span>Let us use the variable x for length. So width will be 1/2x + 3.
Perimeter = x+x+ 1/2x + 3 +1/2x + 3 = 3x + 6 = 66
Therefore 3x = 66-6 = 60
So x = 60/3 = 20
The length is 20 cm.
Therefore the width = 1/2 of 20 + 3 = 10 + 3 = 13 cm
Check: 20+20+13+13 = 66</span>
(-7/8) / (-1 2/5) = (-7/8) / (-7/5) = (-7/8) * (-5/7) = 5/8
