Răspuns:
Explicație pas cu pas:
13) c) 2(1-4x)≤x-25
2-8x≤x-25, 2+25≤x+8x, 30≤9x
x≥30/9, x≥10/3, x∈[10/3, +∞)
d) 7(7-x)≥3x+29, 49-7x≥3x+29, 49-29≥3x+7x, 20≥10x, x≤20:10, x≤2, x∈(-∞, 2]
12 d)
[tex]\sqrt{6} (7\sqrt{3} -5x) \leq 6\sqrt{2} \\7\sqrt{6*3} -5x\sqrt{6} \leq 6\sqrt{2}\\\\7\sqrt{2*3*3} -5x\sqrt{6} \leq 6\sqrt{2} \\7*3\sqrt{2} -5x\sqrt{6} \leq6\sqrt{2} \\21\sqrt{2} -5x\sqrt{6} \leq 6\sqrt{2} \\-5x\sqrt{6} \leq 6\sqrt{2} -21\sqrt{2} \\-5x\sqrt{6} \leq -15\sqrt{2} /:(-5\sqrt{2})\\ x\sqrt{3} \geq 3, \\x\geq \frac{3}{\sqrt{3}} , x apartine [\frac{3}{\sqrt{3}} , + infinit)[/tex]
