If y ∝ x² and y = 8 when x = 2 find y when x = 3?
- 17
- 18
- 19
- None of these
Explanation
y ∝ x² means y = k × x²
Find k:
y = 8 when x = 2
8 = k × 2²
8 = k × 4
k = 2
So y = 2x²
When x = 3:
y = 2 × 3² = 2 × 9 = 18
Last verified on 09-05-2026
y ∝ x² means y = k × x²
Find k:
y = 8 when x = 2
8 = k × 2²
8 = k × 4
k = 2
So y = 2x²
When x = 3:
y = 2 × 3² = 2 × 9 = 18
Last verified on 09-05-2026
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