Answer:
y = + 4
Explanation:
y² - x = 7 ← substitute x = 9 into the equation
y² - 9 = 7 ( add 9 to both sides )
y² = 16 ( take square root of both sides )
y = ± = ± 4
the positive value of y when x = 9 is + 4
4
when x = 9:
⇒ y² - 9 = 7
⇒ y² = 7 + 9
⇒ y² = 16
⇒ y = √16
⇒ y = ±4
Therefore, the positive value of y = 4
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