<span>а) x^2*x^4*x^7=x^(2+4+7)=x^13
</span><span>б) (-2x)^2*(-2x)^3*(-2x)^4=(-2x)^(2+3+4)=(-2x)^9</span>
<span>Дана система ур-ний</span>
<span /><span><span><span><span><span><span>3</span><span>x</span><span>+</span><span>y<span /></span><span>=</span><span>2</span></span><span /></span></span><span /></span><span>3x+y=2</span></span>
<span /><span><span><span><span><span><span>2</span><span>x</span><span>−</span><span>y<span /></span><span>=</span><span>3</span></span><span /></span></span><span /></span><span>2x−y=3</span></span>
<span>Из 1-го ур-ния выразим x</span>
<span /><span><span><span><span><span><span>3</span><span>x</span><span>+</span><span>y<span /></span><span>=</span><span>2</span></span><span /></span></span><span /></span><span>3x+y=2</span></span>
<span>Перенесем слагаемое с переменной y из левой части в правую со сменой знака</span>
<span /><span><span><span><span><span><span>3</span><span>x</span><span>=</span><span>−</span><span>y<span /></span><span>+</span><span>2</span></span><span /></span></span><span /></span><span>3x=−y+2</span></span>
<span /><span><span><span><span><span><span>3</span><span>x</span><span>=</span><span>−</span><span>y<span /></span><span>+</span><span>2</span></span><span /></span></span><span /></span><span>3x=−y+2</span></span>
<span>Разделим обе части ур-ния на множитель при x</span>
<span /><span><span><span><span><span><span><span><span><span><span>3</span><span>x</span></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>=</span><span><span><span><span>1</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span><span>(</span><span>−</span><span>y<span /></span><span>+</span><span>2</span><span>)</span></span></span><span /></span></span><span /></span><span>3x3=13(−y+2)</span></span>
<span /><span><span><span><span><span><span>x</span><span>=</span><span>−</span><span><span><span><span>y<span /></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>+</span><span><span><span><span>2</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span></span><span /></span></span><span /></span><span>x=−y3+23</span></span>
<span>Подставим найденное x в 2-е ур-ние</span>
<span /><span><span><span><span><span><span>2</span><span>x</span><span>−</span><span>y<span /></span><span>=</span><span>3</span></span><span /></span></span><span /></span><span>2x−y=3</span></span>
<span>Получим:</span>
<span /><span><span><span><span><span><span>−</span><span>y<span /></span><span>+</span><span>2</span><span><span><span>(</span></span><span>−</span><span><span><span><span>y<span /></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>+</span><span><span><span><span>2</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span><span>)</span></span></span><span>=</span><span>3</span></span><span /></span></span><span /></span><span>−y+2(−y3+23)=3</span></span>
<span /><span><span><span><span><span><span>−</span><span><span><span><span><span>5</span><span>y<span /></span></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>+</span><span><span><span><span>4</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>=</span><span>3</span></span><span /></span></span><span /></span><span>−5y3+43=3</span></span>
<span>Перенесем свободное слагаемое 4/3 из левой части в правую со сменой знака</span>
<span /><span><span><span><span><span><span>−</span><span><span><span><span><span>5</span><span>y<span /></span></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>=</span><span><span><span><span>5</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span></span><span /></span></span><span /></span><span>−5y3=53</span></span>
<span /><span><span><span><span><span><span>−</span><span><span><span><span><span>5</span><span>y<span /></span></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>=</span><span><span><span><span>5</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span></span><span /></span></span><span /></span><span>−5y3=53</span></span>
<span>Разделим обе части ур-ния на множитель при y</span>
<span /><span><span><span><span><span><span><span><span><span><span>−</span><span>1</span><span><span><span><span>5</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>y<span /></span></span><span /></span><span><span><span>−</span><span><span><span><span>5</span><span /></span><span><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>1</span></span><span /></span></span><span /></span><span>−153y−53=−1</span></span>
<span /><span><span><span><span><span><span>y<span /></span><span>=</span><span>−</span><span>1</span></span><span /></span></span><span /></span><span>y=−1</span></span>
<span>Т.к.</span>
<span /><span><span><span><span><span><span>x</span><span>=</span><span>−</span><span><span><span><span>y<span /></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>+</span><span><span><span><span>2</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span></span><span /></span></span><span /></span><span>x=−y3+23</span></span>
<span>то</span>
<span /><span><span><span><span><span><span>x</span><span>=</span><span>−</span><span><span><span><span><span>−</span><span>1</span></span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span><span>+</span><span><span><span><span>2</span><span /></span><span><span>3</span><span /></span><span><span /><span /></span></span></span></span><span /></span></span><span /></span><span>x=−−13+23</span></span>
<span /><span><span><span><span><span><span>x</span><span>=</span><span>1</span></span><span /></span></span><span /></span><span>x=1</span></span>
<span>Ответ:</span>
<span /><span><span><span><span><span><span>x</span><span>=</span><span>1</span></span><span /></span></span><span /></span><span>x=1</span></span>
<span /><span><span><span><span><span><span>y<span /></span><span>=</span><span>−</span><span>1</span></span><span /></span></span><span /></span></span><span>
</span>
8- 4 ......................7- ещё не решила
√2x-5>√5x+4
2x-5>5x+4
2x-5x>5+4
-3x>9
x>-3