求x为何值时代数式2x 9 x 3--搜答案-搜搜做题作业网

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