Answer:
B
Step-by-step explanation:
1^2 + 8^2 = c^2
1 + 64 = c^2
65 = c^2
√c^2 = √65
Lila did it correctly. The answer is 324
Following PEMDAS, we first focus on the parenthesis. So we simplify 9-3 to get 6
So we go from
18*4^2+(9-3)^2
to
18*4^2+6^2
The next step is applying exponents. In this case, squaring the terms, so we go from
18*4^2+6^2
to
18*16+36
Next is multiplying
18*16+36
turns into
288+36
Finally, add up 288 and 36 to get 288+36 = 324
That confirms that Lila is correct
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The error that Rob made is that he computed 18*4^2+9^2-3^2 but it is NOT correct. Saying (x-y)^2 = x^2-y^2 isn't a true equation for all x and y. Again you have to simplify what is in the parenthesis first, and then you can square it. Or you must use the FOIL rule to expand out (9-3)^2
Simplifying
5x + 2(8x + -9) = 3(x + 4) + -5(2x + 7)
Reorder the terms:
5x + 2(-9 + 8x) = 3(x + 4) + -5(2x + 7)
5x + (-9 * 2 + 8x * 2) = 3(x + 4) + -5(2x + 7)
5x + (-18 + 16x) = 3(x + 4) + -5(2x + 7)
Reorder the terms:
-18 + 5x + 16x = 3(x + 4) + -5(2x + 7)
Combine like terms: 5x + 16x = 21x
-18 + 21x = 3(x + 4) + -5(2x + 7)
Reorder the terms:
-18 + 21x = 3(4 + x) + -5(2x + 7)
-18 + 21x = (4 * 3 + x * 3) + -5(2x + 7)
-18 + 21x = (12 + 3x) + -5(2x + 7)
Reorder the terms:
-18 + 21x = 12 + 3x + -5(7 + 2x)
-18 + 21x = 12 + 3x + (7 * -5 + 2x * -5)
-18 + 21x = 12 + 3x + (-35 + -10x)
Reorder the terms:
-18 + 21x = 12 + -35 + 3x + -10x
Combine like terms: 12 + -35 = -23
-18 + 21x = -23 + 3x + -10x
Combine like terms: 3x + -10x = -7x
-18 + 21x = -23 + -7x
Solving
-18 + 21x = -23 + -7x
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '7x' to each side of the equation.
-18 + 21x + 7x = -23 + -7x + 7x
Combine like terms: 21x + 7x = 28x
-18 + 28x = -23 + -7x + 7x
Combine like terms: -7x + 7x = 0
-18 + 28x = -23 + 0
-18 + 28x = -23
Add '18' to each side of the equation.
-18 + 18 + 28x = -23 + 18
Combine like terms: -18 + 18 = 0
0 + 28x = -23 + 18
28x = -23 + 18
Combine like terms: -23 + 18 = -5
28x = -5
Divide each side by '28'.
x = -0.1785714286
Simplifying
x = -0.1785714286
Answer:
17 %
Step-by-step explanation:
12 of 72 cars needed mufflers
% = cars needing mufflers/total cars × 100 %
= 12/72 × 100 %
= 17 %
17 % of the cars serviced needed muflers.