a+b=4 ab（a+b）=-16 a²+b²=? Use the complete square formula!

a+b=4 ab（a+b）=-16 a²+b²=? Use the complete square formula!

a+b=4
ab（a+b）=-16
So AB = - 4
a+b=4
Square on both sides
a²+2ab+b²=16
a²+b²
=16-2ab
=16+8
=24

How to solve 2x & # 178; + 9x-2 = 0
Try to multiply the cross in detail

First of all, this problem can not use cross multiplication, or cross multiplication is extremely troublesome. It's better to use formula to solve it
The solution of ax & # 178; + bx-c = 0 can be obtained according to the formula x = - B ± √ (b ^ 2-4ac) / 2A

2X & # 178; + 9x + 7 = 0 solution + process

2x²+9x+7=0
(2x+7)(x+1)=0
X = - / 7 / or - 1