Question

The solution of y²-2y=8
a) 0 or 2
b) 5 and 10
c) 0 and -2
d) 2 and 5​

Answer 1

y = - 2 and y = 4

Explanation:

Given

y² - 2y = 8 ( subtract 8 from both sides )

y² - 2y - 8 = 0

Consider the factors of the constant term (- 8) which sum to give the coefficient of the y- term (- 2)

The factors are - 4 and + 2, since

- 4 × 2 = - 8 and - 4 + 2 = - 2, thus

(y - 4)(y+ 2) = 0 ← in factored form

Equate each factor to zero and solve for y

y + 2 = 0 ⇒ y = - 2

y - 4 = 0 ⇒ y = 4

None of the solutions on the given list are correct

Answer 2

b

Explanation:

(y-10)(y-5)=0

y=10,y=5