求x为何值时代数式2x 9 x 3-
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已知x=2时,2x²+3x+m=10m=-4当x=-2时2x²+3x+m=2*(-2)²+3*(-2)-4=-2
x/3-(2x-1)>=0x-3(2x-1)>=0x-6x+3>=0-5x+3>=05x
x=2时代数式2x的平方+5x+c的值时148+10+c=14c=-4∴x=-2时2x的平方+5x+c=8-10-4=-6
∵A=2x2-3x,B=x2-x+1,∴A-3B=(2x2-3x)-3(x2-x+1)=2x2-3x-3x2+3x-3=-x2-3,当x=-1时,原式=-(-1)2-3=-4.
x-7/5-1+2x-1/2+3=0两边乘102(x-7)-10+5(2x-1)+30=02x-14-10+10x-5+30=012x=-1x=-1/12
x=1时,2x²+5x+c=10,通过该已知条件,可以求出c的数值.即:将x=1代入到方程之中2+5+c=10,可知:c=3.将c=3再代回原等式,可得:2x²+5x+c变为:2x
-ax^3-[7-(bx+2ax^3)]=-ax^3-7+bx+2ax^3=ax^3+bx-7x=2时,a*2^3+2b-7=5,即a*2^3+2b=12x=-2时,原式=a*(-2)^3+b*(-2
X=2时代数式2x的平方+5x+c的值是14∴8+10+c=14∴c=-4当x=-2时原式=2x的平方+5x-4=8-10-4=-6
2x²-6x+7=2(x²-3x)+7=2(x²-3x+9/4-9/4)+7=2(x²-3x+9/4)-9/2+7=2(x-3/2)²+5/2≥5/2
5/6X-1=4+5/1x5/6x-5/1x=4+1-(25/6)x=5x=5×(-6/25)x=-(6/5)
7x-11(x+3)-19/9
(1+3k)/5>2k-11+3k>10k-57k
(x-7)/5-1=(2x-1)/2+3两边乘以102(x-7)-10=5(2x-1)+302x-14-10=10x-5+308X=-49x=-49\8
(2x+y-1)(2x-y+1)=4x^2-(y-1)^2当x=2分之1,y=1时4x^2-(y-1)^2=4*1/4-0=1
设y=ax^5+bx^3y1=a(3)^5+b(3)^3当x=3时y1+3=14y1=11y2=a(-3)^5+b(-3)^3=-y1=-11当x=-3时y2+3=-11+3=-8
ax^5+bx^3+cx+2=5所以ax^5+bx^3+cx=3都是奇数次项所以当x变成相反数时ax^5+bx^3+cx=-3则ax^5+bx^3+cx+2=-1
x-2/3=(1/2)x+3/4解得x=17/6
5分之1-2x=05分之1=2xx=5分之1÷2x=10分之1
当X=-2时,带入等式可得:-8a-2b+8=28,即可得8a+2b=8-28=-20当X=2时,8a+12+2b+1=8a+2b+13=-20+13=-7故答案为-7