1.已知(x‐5)(x‐3)=x^2+6x+c.求b和c的值.2.若2x+3y‐5=0,求2^(2x)*8^y的值.
问题描述:
1.已知(x‐5)(x‐3)=x^2+6x+c.求b和c的值.2.若2x+3y‐5=0,求2^(2x)*8^y的值.
答
1.已知(x-5)(x-3)=x^2+bx+c.求b和c的的值.
(x-5)(x-3)=x^2-8x+15
由x^2-8x+15=x^2+bx+c得
b=-8,c=15
2.若2x+3y-5=0,求2^(2x)*8^y的值.
由2x+3y-5=0得2x+3y=5
2^(2x)*8^y
=2^(2x)*3^(3y)
=2^(2x+3y)
=2^5
=32