30=100÷
×=10
×=3
450÷27= 16.666
отв должен быть 16
a) 156² - 56² = (156 - 56)(156 + 56) = 100 * 212 =21200
б)
1) <span>6√2+5√18=</span>6<span>√2+5<span>√(2*9)=6√2+5*3√2=6√2+15√2=21√2</span></span>
<span><span>2) <span>5√75-2√27=<span>5√(25*3)-2√(3*9)=25<span>√3-6√3=19<span>√3</span></span></span></span></span></span><span><span><span><span><span><span>3) <span>√2+√50-√18=<span>√2+√(25*2)-√(2*9)=<span>√2+5√2-3√2=3<span>√2</span></span></span></span></span></span></span></span></span></span><span><span><span><span><span><span><span><span><span><span>4) <span>3√20+5√45-2√80=<span>3√(4*5)+5√(9*5)-2√(5*16)=<span>6√5+15√5-8√5=1<span>3√5</span></span></span></span></span></span></span></span></span></span></span></span></span></span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>5) <span>2√48+√27+√12=<span>2√(16*3)+√(9*3)+√(3*4)=<span>8√3+3√3+2√3=13<span>√3</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>6) <span>(√3-1) (√3+1)= по формуле разность квадратов=3-1=2</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
y=-x²+4x-5=-(x²-4x+5)=-[(x-2)²+1], y=1-(x-2)², y-1= -(x-2)²