Let <em>a</em> and <em>b</em> be the two numbers. Then
<em>a</em> + <em>b</em> = -4
<em>a b</em> = -2
Solve the second equation for <em>b</em> :
<em>b</em> = -2/<em>a</em>
Substitute this into the first equation:
<em>a</em> - 2/<em>a</em> = -4
Multiply both sides by <em>a</em> :
<em>a</em>² - 2 = -4<em>a</em>
Move 4<em>a</em> to the left side:
<em>a</em>² + 4<em>a</em> - 2 = 0
Use the quadratic formula to solve for <em>a</em> :
<em>a</em> = (-4 ± √(4² - 4(-2))) / 2
<em>a</em> = -2 ± √6
If <em>a</em> = -2 + √6, then
-2 + √6 + <em>b</em> = -4
<em>b</em> = -2 - √6
In the other case, we end up with the same numbers, but <em>a</em> and <em>b</em> are swapped.
Surface area = 2(19 x 15) + 2(15 x 13) + 2(13 x 19)
Surface area = 570 + 390 + 494
Surface area = 1454 cm²
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Answer: Surface area = 1454 cm²
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Answer:
She is right, it won´t always work.
Step-by-step explanation:
Hi, in the examples this tactic works because the first numbers, when multiplied, don´t equal 10 (7x6=42 and 8x7=56). If you multiply both numbers and give you 10, you will have to add another zero to the final number and the trick would crash.
Example:
200 x 500 = 100,000
(2 Zeros) (2 zeros) (5 zeros)
Best of luck.
5 divided by 3 is .6. I hope this makes sense. Good luck. I apologize if this is wrong
