Question

7x² + 4x – 20 = 0

Answer 1

Given: 7x² + 4x – 20 = 0

On splitting the middle term 4x as 14x – 10x, we get:

7x² + 14x – 10x – 20 = 0

$\Rightarrow$7x(x + 2) – 10(x + 2) = 0

$\Rightarrow$(x + 2) (7x – 10) = 0

We know that if the product of two numbers is zero, then at least one of them must be zero.

Thus,

x + 2 = 0 or 7x – 10 = 0
$\Rightarrow$x = –2 or x = $\frac{10}{7}$
Therefore, the solution of the given equation is x = –2, $\frac{10}{7}$.