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13 votes
If f(x) = ax + b where a and b are Costants f(1) = 6and f(-2)=3, find the value of a and b?​

User Wig
by
6.4k points

1 Answer

11 votes

Answer:

a = 1

b = 5

⇒ f(x) = x + 5

Explanation:

Given

  • f(x) = ax + b
  • f(1) = 6
  • f(-2) = 3

Therefore,

f(1) = 6 ⇒ a + b = 6

f(-2) = 3 ⇒ -2a + b = 3

Rewrite a + b = 6 to make a the subject, substitute into -2a + b = 3 and solve for b:

a = 6 - b

⇒ -2(6 - b) + b = 3

⇒ -12 + 2b + b = 3

⇒ -12 + 3b = 3

⇒ 3b = 15

⇒ b = 5

Substitute found value for b into a + b = 6 and solve for a:

⇒ a + 5 = 6

⇒ a = 1

Therefore, f(x) = x + 5

User Johndbritton
by
7.2k points
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