Mathematics: Faye and andrew have written down the same negative number. faye squares the number then multiplies by 2 and adds 4. andrew multiples the number by 21 then subtracts the result from 40. they both finish with the same answer. what was the number?

Faye and andrew have written down the same negative

Ответ:

smartcookie8251

31.12.2021

X - the number

Faye squares the number: x²
then multiplies by 2: 2x²
and adds 4: 2x²+4

Andrew multiplies the number by 21: 21x
then subtracts the result from 40: 40-21x

They both finish with the same answer, so the results are equal.
$2x^2+4=40-21x \\
2x^2+21x+4-40=0 \\
2x^2+21x-36=0 \\
2x^2+24x-3x-36=0 \\
2x(x+12)-3(x+12)=0 \\
2x-3=0 \ \lor \ x+12=0 \\
2x=3 \ \lor \ x=-12 \\
x=\frac{3}{2} \ \lor \ x=-12$

The number is negative so x=-12.

The number is -12.

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Ответ:

carelee9449

27.03.2023

Mathematics

(-2,10)(0,6)(3,0)(8,-10)(10,-14)

Step-by-step explanation:

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Faye and andrew have written down the same negative number.
faye squares the number then multiplies by 2 and adds 4.
andrew multiples the number by 21 then subtracts the result from 40.
they both finish with the same answer. what was the number?

Ответ:

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