Question

Quadratic formula 2x^2-9x-35=0

Answer 1

So x = -5/2, 7.

Explanation:

2x^2 - 9x - 35 = 0

Let's see if we can factor this.

We need 2 numbers whose product is 2* -35 ( that is -70) and whose sum is -9.

They are -14 and 5, so we write:

2x^2 - 14x + 5x - 35 = 0

Now we factor by grouping:

2x(x - 7) + 5(x - 7) = 0

(2x + 5)(x - 7) = 0

So x = -5/2, 7.

Answer 2

Hello,

2x² - 9x - 35 = 0

a = 2 ; b = -9 ; c = -35

∆ = b² - 4ac = (-9)² - 4 × 2 × (-35) = 361 > 0

x1 = (-b - √∆)/2a = (9 - 19)/4 = -10/4 = -5/2

x2 = (-b + √∆)/2a = (9 + 19)/4 = 28/4 = 7

S = {-5/2 ; 7}