X(70-X)÷2=528
25﹢25(1+X)﹢25(1+X)²=91
(6-X)﹙2X﹚÷2﹦8
写上步骤 越详细越好
X(70-X)÷2=528
25﹢25(1+X)﹢25(1+X)²=91
(6-X)﹙2X﹚÷2﹦8
写上步骤 越详细越好
1. 70X-X^2=1056
X^2-70X+1056=0
(X-48)(X-22)=0
X=48, X=22
2. 令Y=1+X
25Y^2+25Y+25=91
25Y^2+25Y-66=0
(5Y+11)(5Y-6)=0
Y=-11/5 Y=6/5
X=-11/5 -1 =-16/5
X= 6/5 -1= 1/5
3. (6-X)(2X)/2=8
(6-X)X=8
X^2-6X+8=0
(X-2)(X-4)=0
X=2 X=4