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\(P\left(x\right)=3x^5+x^4-2x^2+2x-1\)
\(Q\left(x\right)=-3x^5+2x^2-2x+3\)
\(P\left(x\right)+Q\left(x\right)=3x^5+x^4-2x^2+2x-1-3x^5+2x^2-2x+3\)
\(=x^4+2\)
\(P\left(x\right)-Q\left(x\right)=3x^5+x^4-2x^2+2x-1+3x^5-2x^2+2x-3\)
\(=6x^5+x^4-4x^2+4x-4\)
Thu gọn + sắp xếp luôn
P(x) = 3x5 + x4 - 2x2 + 2x - 1
Q(x) = -3x5 + 2x2 - 2x + 3
P(x) + Q(x) = ( 3x5 + x4 - 2x2 + 2x - 1 ) + ( -3x5 + 2x2 - 2x + 3 )
= ( 3x5 - 3x5 ) + x4 + ( 2x2 -- 2x2 ) + ( 2x - 2x ) + ( 3 - 1 )
= x4 + 2
P(x) - Q(x) = ( 3x5 + x4 - 2x2 + 2x - 1 ) - ( -3x5 + 2x2 - 2x + 3 )
= 3x5 + x4 - 2x2 + 2x - 1 + 3x5 - 2x2 + 2x - 3
= ( 3x5 + 3x5 ) + x4 + ( -2x2 - 2x2 ) + ( 2x + 2x ) + ( -1 - 3 )
= 6x5 + x4 - 4x2 + 4x - 4
Bài 1:
a)
\(F+G+H=(x^3-2x^2+3x+1)+(x^3+x-1)+(2x^2-1)\)
\(=2x^3+4x-1\)
b)
\(F-G+H=0\)
\(\Leftrightarrow (x^3-2x^2+3x+1)-(x^3+x-1)+(2x^2-1)=0\)
\(\Leftrightarrow 2x+1=0\)
\(\Leftrightarrow x=-\frac{1}{2}\)
Bài 2:
a)
\(A=-4x^5-x^3+4x^2-5x+9+4x^5-6x^2-2\)
\(=(-4x^5+4x^5)-x^3+(4x^2-6x^2)-5x+(9-2)\)
\(=-x^3-2x^2-5x+7\)
\(B=-3x^4-2x^3+10x^2-8x+5x^3\)
\(=-3x^4+(5x^3-2x^3)+10x^2-8x\)
\(=-3x^4+3x^3+10x^2-8x\)
b)
\(P=A+B=(-x^3-2x^2-5x+7)+(-3x^4+3x^3+10x^2-8x)\)
\(=-3x^4+(3x^3-x^3)+(10x^2-2x^2)-(8x+5x)+7\)
\(=-3x^4+2x^3+8x^2-13x+7\)
\(P(-1)=-3.(-1)^4+2(-1)^3+8(-1)^2-12(-1)+7=23\)
\(Q=A-B=(-x^3-2x^2-5x+7)-(-3x^4+3x^3+10x^2-8x)\)
\(=3x^4-(x^3+3x^3)-(2x^2+10x^2)+(8x-5x)+7\)
\(=3x^4-4x^3-12x^2+3x+7\)
a)P(x)=5x^3+3x^2-2x-5
Q(x)=5x^3+2x^2-2x+4
b)P(x)+Q(x)=10x^3+5x^2-4x-1
P(x)-Q(x)=x^2-9
c)x=3
_CÓ AI GIỎI TOÁN THÌ GIÚP MK NHA RẤT CẢM ƠN ______________
a, P(x)= 5+x\(^3\)-2x+4x\(^3\)+3x\(^2\)-10
=(5-10) + (x\(^3\) + 4x\(^3\)) - 2x + 3x\(^2\)
= -5 + 5x\(^3\) - 2x + 3x\(^2\)
sắp xếp : P(x) = -5 - 2x + 3x\(^2\) + 5x\(^3\)
Q(x)=4-5x\(^3\)+2x\(^2\)-x\(^3\)+6x+11x\(^3\)-8x
= 4 - (5x\(^3\)-x\(^3\)+11x\(^3\)) + 2x\(^2\) + (6x - 8x)
= 4 - 15x\(^3\) + 2x\(^2\) - 2x
Sắp xếp : Q(x) = 4 - 2x + 2x\(^2\) -15 x\(^3\)
b, P(x) + Q(x) = ( -5-2x+3x\(^2\)+5x\(^3\)) + (4-2x+2x\(^2\)-15x\(^3\))
= -5 -2x + 3x\(^2\) + 5x\(^3\) + 4 - 2x + 2x\(^2\) - 15x\(^3\)
= (-5 + 4) + (-2x-2x) + (3x\(^2\)+ 2x\(^2\)) + (5x\(^3\) - 15x\(^3\))
=- 1 -4x+ 5x\(^2\) - 10x\(^3\)
P(x) - Q(x) = (-5-2x+3x\(^2\)+5x\(^3\)) - (4-2x+2x\(^2\)-15x\(^3\))
= -5-2x+3x\(^2\)+5x\(^3\)- 4+2x-2x\(^2\)+15x\(^3\)
= (-5-4) + (-2x+2x) + (3x\(^2\)-2x\(^2\)) + (5x\(^3\)+15x\(^3\))
= -9 + x\(^2\) + 20x\(^3\)
a, \(P\left(x\right)=5x^5-4x^2+7x+1;Q\left(x\right)=5x^5-4x^2+3x+8\)
b, \(P\left(x\right)+Q\left(x\right)=10x^5-8x^2+10x+9\)
c, \(P\left(x\right)=Q\left(x\right)\Rightarrow7x+1=3x+8\Leftrightarrow4x=7\Leftrightarrow x=\dfrac{7}{4}\)
a/ \(P\left(x\right)=8x^5+7x-6x^2-3x^5+2x^2+1\)
\(=8x^5-3x^5-6x^2+2x^2+7x+1\)
\(=5x^5-4x^2+7x+1\)
\(Q\left(x\right)=4x^5+3x-2x^2+x^5-2x^2+8\)
\(=4x^5+x^5-2x^2-2x^2+3x+8\)
\(=5x^5-4x^2+3x+8\)
b/ \(P\left(x\right)=5x^5-4x^2+7x+1\)
+ \(Q\left(x\right)=5x^5-4x^2+3x+8\)
____________________________
\(P\left(x\right)+Q\left(x\right)=10x^5-8x^2+10x+9\)
c/ \(P\left(x\right)=Q\left(x\right)\)
\(\Rightarrow5x^5-4x^2+7x+1=5x^5-4x^2+3x+8\)
\(\Rightarrow7x+1=3x+8\)
\(\Rightarrow4x-7=0\)
\(\Rightarrow x=\dfrac{7}{4}\)