ответ 28. Корень из 98 надо представить как корень из 49 умноженных на 2, тогда корень из 2 взаимно уничтожается и остается 4 корня из 49, т. е. 4 умноженное на 7.
X - 1 число; у - 2 число; составляем систему: x+y=80; 0,5x+2y=115; выражаем x из 1 уравнения: x=80-y; подставляем во 2: 40-0,5y+2y=115; 1,5y=75; y=50; x=80-50=30; проверяем: 50+30=80; 15+100=115; Ответ: 50 и 30
<span>Если формулу разности квадратов <span> <span>(a</span> – <span><span>b)</span><span>(a</span></span> + <span>b)</span> = <span>a 2</span> – <span>b 2</span> </span>
записать справа налево, то получится тождество
<span> <span>a 2</span> – <span>b 2</span> = <span>(a</span> – <span>b)</span> <span>(a</span> + <span>b)</span> </span>,
которое позволяет разложить разность квадратов на множители.
Оно читается так:
| <span> разность квадратов двух выражений равна произведению </span>
| <span> разности этих выражений и их суммы. </span>
<span> Примеры:
1) </span><span> 16<span>x 6</span> – <span>9<span>y 4</span></span> = <span><span>(<span>4<span>x 3</span></span>)</span> 2</span> – <span><span>(<span>3<span>y 2</span></span>)</span> 2</span> = <span>(<span>4<span>x 3</span></span></span> – <span><span>3<span>y 2</span></span>)</span> <span>(<span>4<span>x 3</span></span></span> + <span><span>3<span>y 2</span></span>)</span> ; </span>
<span> 2) </span><span> <span><span>1 <span>916</span></span><span>a 4</span></span> – <span><span>1 <span>79</span></span><span>b 6</span></span> = <span><span>2516</span><span>a 4</span></span> – <span><span>169</span><span>b 6</span></span> = <span><span>(<span> <span>54</span><span>a 2</span></span>)</span> 2</span> – <span><span>(<span> <span>43</span><span>b 3</span></span>)</span> 2</span> =
= <span>(<span> <span>54</span><span>a 2</span></span></span> – <span><span><span>43</span><span>b 3</span></span>)</span> <span>(<span> <span>54</span><span>a 2</span></span></span> + <span><span><span>43</span><span>b 3</span></span>)</span> ; </span>
<span> 3) </span><span> <span>975 2</span> – <span>25 2</span> = <span>(975</span> – <span>25)</span> <span>(975</span> + <span>25)</span> = 950 • 1000 = 950 000 ; </span>
<span> 4) </span><span> <span><span><span>4<span>x 4</span></span>−<span>9<span>y 4</span></span></span><span><span>2<span>x 2</span></span>−<span>3<span>y 2</span></span></span></span> = <span><span><span>(<span><span>2<span>x 2</span></span>−<span>3<span>y 2</span></span></span>)</span><span>(<span><span>2<span>x 2</span></span>+<span>3<span>y 2</span></span></span>)</span></span><span><span>2<span>x 2</span></span>−<span>3<span>y 2</span></span></span></span> = <span><span>2<span>x 2</span></span>+<span>3<span>y 2</span></span></span> .
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Ответ:
Объяснение:
3x−ay+bz, если
a=3c,b=11c3 и x=5c3+2,y=6c2−c+14,z=5c−1
3×(5c³+2)-3c×(6c²−c+14)+11c³(5c−1)=15c³+6-18c³+3c²-42c+55-11c³=55[tex]c^{4}-15c³+3c²-42c
Lg(x)=lg(m)+2lg(n)-3lg(a)
lg(x)=lg(mn^2/a^3)
x=mn^2/a^3