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BECE Mathematics 2020 Paper

Question : 33

Total: 40

2 y = 1 - 3 x^2 + 4 x

y

x = -1

Solution:

Concept

x -= +(

When a negative number [-] multiplies another negative number[-], the sign becomes positive [+])

- x += -

(When a negative number

[-]

multiplies a positive number [+], the sign becomes negative

[-]

)

\; a^2 = a \times a

\; 2 y = 1 - 3 x^2 + 4 x

When

x = -1

, substitute

x

by -1

\; 2 y = 1 - 3(-1)^2 + 4(-1)

\; (-1)^2 = -1 x -1 = +1

\; 4(-1) = 4 x -1 = -4

\; 2 y = 1 - 3 x^2 + 4 x

\; \Rightarrow 2 y = 1 - 3(1) - 4

\; 2 y = 1 - 3 - 4

\; 2 y = 1 - 7

\; 2 y = -6

Divide both sides by 2 to get rid of the 2 multiplying

y

\Rightarrow y = \frac{-6}{2} = -3

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