Question

Using the quadratic formula, solve 0 = 2x²8x + 5 Give each of your answers to 2 d.p.​

Answer 1

(i) 4x

2

−5x−3=0

Let us consider, a=4,b=−5,c=−3

So, by using the formula,

x=

2a

−b±

b

2

−4ac

​

​

So let, b

2

−4ac=D

x=

2a

−b±

D

​

​

D

​

=b

2

−4ac

=(−5)

2

−4(4)(−3)

=25+48

=73

​

So

x=[−(−5)±

73

​

]/2(4)

=[5±8.54]/8

=[5+8.54]/8 or [5−8.54]/8

=13.54/8 or −3.54/8

=1.6925 or -0.4425

∴ Value of x=1.69 or -0.44

Hope it helps