intercepts of 3x^2+6x
On the horizontal axis, y = 0: solve 3x2 + 6x = 0
1) Let's solve in ℝ: 3x2 + 6x = 0
You can factorize the expression: 3x2 + 6x into: x·(3x + 6)
A product is zero if and only if one of its factors is zero: we solve each factor equal to 0
⇥1.1) Let's solve in ℝ: x = 0
⇥Solution found: x = 0
⇥1.2) Let's solve in ℝ: 3x + 6 = 0
⇥ 3x = -6
⇥ⓘ Both sides are divided by 3
⇥ x = -63
⇥ⓘ We simplify the fraction by dividing the numerator and the denominator by 3, their greatest common divisor: -63 = -2
⇥Solution obtained: x = -2
On the vertical axis, x = 0: calculate f(0)
⇥ 3·02 + 6·0
⇥ⓘ A product with a zero factor is zero: 3·0 = 0, 6·0 = 0
⇥ 0 + 0
⇥ⓘ Adding 0 changes nothing: 0 + 0 = 0
⇥ 0
▶Axis intercepts:   { (-2, 0), (0, 0) }