The value of a for which the lines x=1, y=2 and a2x+2y−20=0 are concurrent is:
4
Since x=1, y=2 and a2x+2y−20=0 are concurrent
∴ x=1 and y=2 lie on the line a2x+2y−20=0
⇒ x=1 and y=2 is a solution of given equation.
On substituting x=1 and y=2 in equation a2x+2y−20=0, we get
⇒a2×1+2×2−20=0⇒a2−16=0
⇒a2=16⇒a=−4 or 4