Question 65

If 5Δ1 = 40, 9Δ9 = 0 and 7Δ1 = 60, then ﬁnd the value of 4Δ9 = ?

Solution

Given : 5Δ1 = 40, 9Δ9 = 0 and 7Δ1 = 60

If we replace 'Δ' with '-', and multiply the difference by 10, we get the desired result.

Eg :- $$(5-1)\times10=40$$

and $$(9-9)\times10=0$$ and $$(7-1)\times10=60$$

Similarly, $$(4-9)\times10=-50$$

=> Ans - (C)

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