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\text { (i) } x(2 x+5)=25

(ii) (x + 3) (x – 3) = 40

Answer:

\text { (i) } x(2 x+5)=25

Let us simplify the given equation,

\begin{aligned} &2 x^{2}+5 x-25=0\\ &\text { By factorizing, we get }\\ &2 x^{2}+10 x-5 x-25=0 \end{aligned}

2x(x + 5) – 5 (x + 5) = 0

(x + 5) (2x - 5) = 0

So,

(x + 5) = 0 or (2x - 5) = 0

x = -5 or 2x = 5

x = -5 or x = 5/2

∴ Value of x = -5, 5/2

(ii) (x + 3) (x – 3) = 40

Let us simplify the given equation,

\begin{aligned} &\begin{array}{l} x^{2}-3 x+3 x-9=40 \\ x^{2}-9-40=0 \\ x^{2}-49=0 \\ x^{2}=49 \\ x=\sqrt{49} \\ \quad=\pm 7 \end{array}\\ &\therefore \text { Value of } x=7,-7 \end{aligned}

"hello students welcome to lido learning
india's best online classroom our
question for today
is we need to solve these two given
equation and find the value of x the
first equation says
that x in the bracket
x plus 2 oh sorry 2 x plus 5
bracket close is equals to 25
that is
x 2x plus 5
is equals to 25 right if we solve this
equation we'll get the value as 2x
square
plus 5x minus 25
is equals to zero okay factorizing this
equation will get it as 10
and 5 that is 2x squared plus
10x minus 5x
minus 25 is equal to zero
let's take the common so 2x is the
common and in the bracket we will left
with x
plus 5 again here
minus 5 is the common and in the bracket
we are left with x plus 5 which is
equals to 0
so what we are left with we are left
with 2x minus 5
and in the another bracket we have x
plus 5
whole equals to 0. so if 2x
minus 5 is equals to 0 value of x will
be
5 upon 2 and if x
plus 5 is equals to 0 then value of x is
yes it is minus 5.
let's solve the next question the next
part of this question
says that x plus 3
x minus 3 is equals to 40.
let's solve this equation first so it
will be x
square minus 3x
plus 3x
minus 9 is equals to 40
yeah or we can write it as x square
minus 49 is equals to zero
we can write it as x minus seven
[Music]
or x plus seven now you will be thinking
why i have written this
so it is from the property a square
minus b square
is equals to a minus b multiplied by
a plus b okay so
and 49 is b where b is 7
right 7 square in place of 49 we can
write 7 square so if
if x minus 7 is equal to 0 the value of
x will be
7 and if x plus 7 is equals to 0 value
of seven will be
minus seven value of x will be minus
seven so here we have two values of x
that is plus and minus seven
thank you so much i hope that this has
solved all your doubts for more such
questions do subscribe leader learning"

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