x^2-7x-18=0 by factorisation method
Answers
Answer:
x^2-9x+2x-18
x(x-9)+2(x-9)
(x-9)(x+2)
Step-by-step explanation:
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Answer:
=
9
x=9
x=9
=
−
2
Step-by-step explanation:
How to solve your problem
2
−
7
−
1
8
=
0
x^{2}-7x-18=0
x2−7x−18=0
Quadratic formula
Factor
1
Use the quadratic formula
=
−
±
2
−
4
√
2
x=\frac{-{\color{#e8710a}{b}} \pm \sqrt{{\color{#e8710a}{b}}^{2}-4{\color{#c92786}{a}}{\color{#129eaf}{c}}}}{2{\color{#c92786}{a}}}
x=2a−b±b2−4ac
Once in standard form, identify a, b and c from the original equation and plug them into the quadratic formula.
2
−
7
−
1
8
=
0
x^{2}-7x-18=0
x2−7x−18=0
=
1
a={\color{#c92786}{1}}
a=1
=
−
7
b={\color{#e8710a}{-7}}
b=−7
=
−
1
8
c={\color{#129eaf}{-18}}
c=−18
=
−
(
−
7
)
±
(
−
7
)
2
−
4
⋅
1
(
−
1
8
)
√
2
⋅
1
x=\frac{-({\color{#e8710a}{-7}}) \pm \sqrt{({\color{#e8710a}{-7}})^{2}-4 \cdot {\color{#c92786}{1}}({\color{#129eaf}{-18}})}}{2 \cdot {\color{#c92786}{1}}}
x=2⋅1−(−7)±(−7)2−4⋅1(−18)
2
Simplify
Evaluate the exponent
Multiply the numbers
Add the numbers
Evaluate the square root
Multiply the numbers
=
7
±
1
1
2
x=\frac{7 \pm 11}{2}
x=27±11
3
Separate the equations
To solve for the unknown variable, separate into two equations: one with a plus and the other with a minus.
=
7
+
1
1
2
x=\frac{7+11}{2}
x=27+11
=
7
−
1
1
2
x=\frac{7-11}{2}
x=27−11
4
Solve
Rearrange and isolate the variable to find each solution
=
9
x=9
x=9
=
−
2
x=-2
x=−2
Solution
=
9
=
−
2