Напишите промежутки возрастания и убывания функции y=-3x^2

3x< 113х> -11x> -3 2/3            x∈(-3 2/3; +∞) 4x-9> 5(x-2)4x-9> 5x-10x< 1            x∈(-∞; 1) -4+2(x-2)< 4(1-0,5)-4+2x-4< 22x< 10x< 5          x∈(-∞; 5) (x-6)(x+6)≥(x-6)²x²-36≥x²-12x+3612x≥72x≥6            x∈[6; +∞)2x-1\3-2≤3x-5\2 4x-2-12≤9x-155x≥1x≥0.2            x∈[0.2; +∞)в последнем примере не понятно условие, решил, как понял

0\\\\\\3)\; \; 3sin\frac{\pi}{6}+5cos\frac{\pi}{3}=3\cdot \frac{1}{2}+5\cdot \frac{1}{2}=\frac{8}{2}=4\\\\tg\frac{\pi}{3}-sin\frac{\pi}{3}-cos\frac{\pi}{6}=\sqrt3-\frac{\sqrt3}{2}-\frac{\sqrt3}{2}=\sqrt3-\sqrt3=0" class="latex-formula" id="TexFormula2" src="https://tex.z-dn.net/?f=%5Cctga%3D%5Cfrac%7B1%7D%7Btga%7D%3D%5Cfrac%7B12%7D%7B5%7D%3E0%5C%5C%5C%5C%5C%5C3%29%5C%3B%20%5C%3B%203sin%5Cfrac%7B%5Cpi%7D%7B6%7D%2B5cos%5Cfrac%7B%5Cpi%7D%7B3%7D%3D3%5Ccdot%20%5Cfrac%7B1%7D%7B2%7D%2B5%5Ccdot%20%5Cfrac%7B1%7D%7B2%7D%3D%5Cfrac%7B8%7D%7B2%7D%3D4%5C%5C%5C%5Ctg%5Cfrac%7B%5Cpi%7D%7B3%7D-sin%5Cfrac%7B%5Cpi%7D%7B3%7D-cos%5Cfrac%7B%5Cpi%7D%7B6%7D%3D%5Csqrt3-%5Cfrac%7B%5Csqrt3%7D%7B2%7D-%5Cfrac%7B%5Csqrt3%7D%7B2%7D%3D%5Csqrt3-%5Csqrt3%3D0" title="\ctga=\frac{1}{tga}=\frac{12}{5}>0\\\\\\3)\; \; 3sin\frac{\pi}{6}+5cos\frac{\pi}{3}=3\cdot \frac{1}{2}+5\cdot \frac{1}{2}=\frac{8}{2}=4\\\\tg\frac{\pi}{3}-sin\frac{\pi}{3}-cos\frac{\pi}{6}=\sqrt3-\frac{\sqrt3}{2}-\frac{\sqrt3}{2}=\sqrt3-\sqrt3=0">