Question

If f(x)=ax²+bx+c and f(1)=6,f(2)=11,f(3)=18 find the value of a,b,c​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:-

Given:

f(x) = ax² + bx + c

f(1) = 6

f(2) = 11

f(3) = 18

Substitute x = 1 , 2 , 3 in the given polynomial.

★ f(1) = a(1)² + b(1) + c

⟹ 6 = a + b + c -- equation (1)

Similarly,

★ f(2) = a(2)² + b(2) + c

⟹ 11 = 4a + 2b + c -- equation (2)

★ f(3) = a(3)² + b(3) + c

⟹ 18 = 9a + 3b + c -- equation (3)

Subtract equation (1) from (2).

⟹ 4a + 2b + c - (a + b + c) = 11 - 6

⟹ 4a + 2b + c - a - b - c = 5

⟹ 3a + b = 5 -- equation (4).

From equation (3) ,

⟹ 18 - c = 9a + 3b

⟹ 18 - c = 3(3a + b)

Substitute the value of 3a + b from equation (4).

⟹ 18 - c = 3 * 5

⟹ 18 - 15 = c

⟹ 3 = c

substitute the value of c in equation (1).

⟹ 6 = a + b + 3

⟹ 6 - 3 = a + b

⟹ 3 = a + b -- equation (5)

Subtract equation (5) from equation (4).

⟹ 3a + b - (a + b) = 5 - 3

⟹ 3a + b - a - b = 2

⟹ 2a = 2

⟹ a = 1

Substitute a value in equation (5).

⟹ 1 + b = 3

⟹ b = 3 - 1

⟹ b = 2

Therefore,

• a = 1
• b = 2
• c = 3.