Question

2х+7<=0 помогите! !!!

Answer 1

2х+7<=0 
2x<=-7
x<=-3.5
x=(-oo -3.5]

Answer 2

Solving the Inequality 2x^2 + 5x - 7 <= 0

To solve the inequality 2x^2 + 5x - 7 <= 0, we can use the quadratic formula and the discriminant to find the solution set.

The quadratic formula is given by: x = (-b ± √(b^2 - 4ac)) / (2a)

Where a, b, and c are the coefficients of the quadratic equation ax^2 + bx + c = 0.

For the given inequality 2x^2 + 5x - 7 <= 0, the coefficients are: a = 2, b = 5, and c = -7.

Using the quadratic formula, we can find the roots of the quadratic equation: x = (-5 ± √(5^2 - 4*2*(-7))) / (2*2) x = (-5 ± √(25 + 56)) / 4 x = (-5 ± √81) / 4 x = (-5 ± 9) / 4 x1 = (-5 - 9) / 4 = -14 / 4 = -3.5 x2 = (-5 + 9) / 4 = 4 / 4 = 1

The roots of the quadratic equation are x = -3.5 and x = 1.

The solution set for the inequality 2x^2 + 5x - 7 <= 0 is (-3.5, 1).

Solving the Inequality 5x^2 - 4x + 21 > 0

To solve the inequality 5x^2 - 4x + 21 > 0, we can again use the quadratic formula and the discriminant to find the solution set.

The coefficients for the given inequality 5x^2 - 4x + 21 > 0 are: a = 5, b = -4, and c = 21.

Using the quadratic formula, we can find the discriminant: D = (-4)^2 - 4*5*21 = 16 - 420 = -404

Since the discriminant is negative, the quadratic equation 5x^2 - 4x + 21 = 0 has no real roots, and the inequality 5x^2 - 4x + 21 > 0 is true for all real values of x.

Therefore, the solution set for the inequality 5x^2 - 4x + 21 > 0 is all real numbers.

In summary: - For the inequality 2x^2 + 5x - 7 <= 0, the solution set is (-3.5, 1). - For the inequality 5x^2 - 4x + 21 > 0, the solution set is all real numbers.