If straight line ax + by + c = 0 always passes through (1, -2), then a, b, c are

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9.Straight Line

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If the straight line $ax + by + c = 0$ always passes through $(1, -2),$ then $a, b, c$ are

A

In $A.P.$

B

In $H.P.$

C

In $G.P.$

D

None of these

Solution

(a) $ax + by + c = 0$ is always through $(1,\, – 2)$.

$a – 2b + c = 0$ ==> $2b = a + c$

Therefore, $a, b$ and $c$ are in $A.P.$

Standard 11

Mathematics

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