(3x-4y)^2=(3x-4y)(3x-4y)=3x*3x-3x*4y-4y*3x-4y*(-4y)=9x^2-12xy-12yx+16y^2=
9x^2-24xy+16y^2
3,78/ -1,8=-2,1
ответ :-2,1
<span>1) ac2-ad+c3-cd-bc2+bd= = (ac2 – ad) + (c3 –
bc2) + (bd – cd) = a·(c2 – d) + c2·(c – b) + d·(b – c) = a·(c2 – d) +
c2·(c – b) – d·(c – b) = a·(c2 – d) + c2·(c – b) – d·(c – b) = a·(c2 –
d) + (c – b)·(c2 – d) = (c2 – d)·(a + c – b)</span>
<span>2) mx2+my2-nx2-ny2+n-m= x2 ( m - n ) + y2 ( m - n ) - ( m - n ) = ( m-n ) (x2 + y2 - 1 ) </span>
<span>3) am2+cm2-an+an2-cn+cn2= m2 (a + c ) + n2 ( a + c ) - n ( a + c ) = ( a+ c) ( m2 + n2 - n) </span>
<span>4) <span> xy2-ny2-mx+mn+m2x-m2n= y2 ( x - n ) + m2 ( x - n) - m ( x - n ) = ( x-n) ( y2 + m2 - m ) </span></span>
<span>5) a2b+a+ab2+b+2ab+2=ab ( a + b + 2 ) + ( a+ b+ 2 ) = 2 ( a+ b + 2 ) </span>
6) x2-xy+x-xy2+y3-y2= x ( x – y + 1) – y 2 ( x – y + 1)=( x – y + 1)( x – y 2 ).
Х(а + 5) - 3(а + 5) = (а + 5)(х - 3)
Система:
x - y = 7 +
x + y = -3
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2x = 4
x = 2
2 - y = 7
-y = 5
y = -5
(2;-5) точка пересечения графиков
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Подставляем:
a*2 - 3*(-5) = 4
2a + 15 = 4
2a = -11
a = -5,5