if four times a whole time is substracted from three times the square of the number , the result 15 is obtained . find the number

if four times a whole time is substracted from three times the square

1.	if four times a whole time is substracted from three times the square of the number , the result 15 is obtained . find the number
Answer» 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