Question

if 4 time a whole number is subtracted from three times the square of the number the result 15 is obtained , find the number

*show the solving steps*​

Answer 1

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Answer 2

Step-by-step explanation:

4 times a whole number" ... 4x

"is subtracted from three times the

square of the number" ... 3x2 - 4x

"the result 15 is obtained"

3x2 - 4x = 15

Subtract 15 from both sides

3x2 - 4x - 15 = 0

This can be factored by grouping. Multiply

the coefficient of x2 by the constant:

3(-15) = -45

Look for factors of -45 that add to -4:

-9(5)=-45 ... -9+5 = -4

Replace -4x with -9x+5x and factor by grouping

3x2-9x +5x - 15 = 0

(3x2-9x) + (5x-15) = 0

3x(x-3) + 5(x-3) = 0

(3x+5)(x-3) = 0

Your two answers are found by realizing that

this is true if either

3x+5 = 0 or (x-3) =0

Solve these two simple equations to get the

final two values of x