Question

If foue time a whole numher is subtracted from 3 time the square of the number the result is 15. find the number ​

Answer 1

$\huge \red{\bf Answer :- }$

• That number is 3 or -5/3.

$\pink{\sf Given :- }$

• Four times a whole number is subtracted from 3 times the square of the number the result is 15.

$\pink{\sf To \: Find :- }$

• That number.

$\huge \red{\bf Solution :-}$

Let

• That number be x
• Four times the number = 4x
• three times the square of the number = 3x²

Equation :- 3x² - 4x = 15

According to question :-

⇒ 3x² - 4x = 15

⇒ 3x² - 4x - 15 = 0

⇒ 3x² - 9x + 5x - 15 = 0

⇒ 3x (x - 3) + 5 (x - 3) = 0

⇒ (3x + 5) (x - 3) = 0

_____________________

→ 3x + 5 = 0

⇒ 3x = 0 - 5

⇒ 3x = -5

⇒ x = -5/3

→ x - 3 = 0

⇒ x = 0 + 3

⇒ x = 3

_____________________

Hence, that number is 3 or -5/3.

Answer 2

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