Question

Ex 5 .Dau coroana si 97p.

Answer 1

Răspuns x > 39 / 9

Explicație pas cu pas:

(2x - 1)^ 2 - (x + 2)(x - 3) - 3(x + 2)^2 =

= (4x^2 - 4x + 1) - (x^2 - x - 6) - (3x^2 + 12x + 12)

= - 9x - 29

-9x - 29 < 10

-9x < 39

x > 39 / 9

Answer 2

(a-b)²=a²-2ab+b²

(2x-1)²=4x²-4x+1

(a+b)²=a²+2ab+b²

(x+2)²=x²+4x+4

(x+2)(x-3)=x(x-3)+2(x-3)=x²-3x+2x-6=x²-x-6

E(x)=4x²-4x+1-(x²-x-6)-3(x²+4x+4)

E(x)=4x²-4x+1-x²+x+6-3x²-12x-12

E(x)= - 15x - 5

E(x) < 10

- 15x - 5 < 10   ⇒   - 15x < 10+5   ⇒    -15x < 15    ⇒    x < 15/-15   ⇒    x < -1

x ∈ (-∞; -1)