यदि (D(t)=120-kt) और (D(3)-D(9)=42), तो (k) क्या है?
If (D(t)=120-kt) and (D(3)-D(9)=42), what is (k)?
Explanation opens after your attempt
C. (7)
Concept
(D(3)-D(9)=k(9-3)=6k). From (6k=42), (k=7).
Why this answer is correct
The correct answer is C. (7). (D(3)-D(9)=k(9-3)=6k). From (6k=42), (k=7).
Exam Tip
(D(3)-D(9)=k(9-3)=6k) है। (6k=42) से (k=7) मिलता है।
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