Question

find the number whos squre diminshed by 84 is equle to thrise of 8 more then the given number

Answer 1

Let the number be x

${x}^{2} - 84 = 3(x + 8) \\ {x}^{2} - 84 = 3x + 24 \\ {x}^{2} - 3x - 84 - 24 = 0 \\ {x}^{2} - 3x - 108 = 0 \\ {x}^{2} + 9x - 12x - 108 = 0 \\ x(x + 9) - 12(x + 9) = 0 \\ (x + 9)(x - 12) = 0 \\ x = - 9 \: or \: x = 12$

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Answer 2

Answer:

x=(-9) or x=12

Step-by-step explanation:

Let the number be "x".

Now, square of x diminished by 84: x²-84

is equal to: =

thrice of 8 more than the number: 3(x+8)

Hence, our equation is,

x²-84=3(x+8)

x²-84=3x+24

x²-3x-108=0

x²-12x+9x -108 = 0

x(x - 12) + 9(x - 12) = 0

(x + 9)(x - 12)=0

x=(-9) or x=12

If we have to consider only natural number, then x=12 would be the required answer.

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