WAEC Mathematics 2017 Paper

Concept:Splitting the middle term helps factorise a quadratic expression into two linear factors.Explanation:Given quadratic: $7x^2 + 33x - 10$.Multiply the coefficient of $x^2$ and the constant: $7 \times (-10) = -70$.We need two numbers whose product is $-70$ and sum is $33$.Those numbers are $35$ and $-2$, because $35 \times (-2) = -70$ and $35 + (-2) = 33$.Rewrite the middle term using these numbers: $7x^2 + 35x - 2x - 10$.Factor by grouping: $7x(x + 5) - 2(x + 5)$.Take out the common factor $(x + 5)$: $(7x - 2)(x + 5)$.So the factors are $7x - 2$ and $x + 5$.From the options, $7x - 2$ is option C.Answer:C. $7x - 2$