Question

求此题步骤！！谢谢！！

14.

Answer 1

说说明a,b的方向相反啊则 a=cb，c为负数，就行了，解出m=-1

Answer 2

|向量a-向量b|=|向量a|+|向量b|
|(m-1,-2)|=|(m,-1)|+|(1,1)|
√(m-1)²+4=√m²+1+√2
两边平方
(m-1)²+4=m²+1+2√2*√m²+1+2
5-2m=3+2√2*√m²+1
1-m=√2*√m²+1
再两边平方
m²-2m+1=2(m²+1)
m²+2m+1=0
(m+1)²=0
m=-1
请参考

Answer 3

向量a-b=(1-m,2),
由|a-b|=|a|+|b|得√[(1-m)^2+4]=√(m^2+1)+√2，
平方得(1-m)^2+4=m^2+3+2√[2(m^2+1)],
整理得1-m=√[2(m^2+1)],m<=1,
平方得1-2m+m^2=2m^2+2,
整理得m^2+2m+1=0,
解得m=-1.

Answer 4

a=(m,-1) ,b=(1,1)
a-b= (m-1,-2)
|a-b|=√[ (m-1)^2+4]
|a|=√(m^2+1) , |b|=√2
|a-b| = |a|+|b|
√[ (m-1)^2+4] =√(m^2+1) + √2
(m-1)^2+4 = m^2+3 +2√2.√(m^2+1)
-2m+2 = 2√2.√(m^2+1)
-m+1 =√2.√(m^2+1)
(-m+1)^2 = 2(m^2+1)
m^2 -2m+1 =2m^2 +2
m^2+2m+1=0
m=-1