Question

Pls only do this if yk it because i’m giving correct answer brainliest! :))

Answer 1

Answer:

x=4.3, x=-0.3

Step-by-step explanation:

4x^2-16x-26=-21

add 21 to both sides

4x^2-16x-26+21=-21+21

simplify

4x^2-16x-5=0

solve using the quadratic formula

a=4, b=-16, c=-5

x=-(-16)±√(-16)^2-4·4(-5)/2(4)

(solve using a calculator or using order of operations)

(solve for both - and +)

x=4.3, x=-0.3

Answer 2

Answer:

$x=2+\frac{1}{2}\sqrt[]{21}$

or

$x=2-\frac{1}{2}\sqrt{{21}$

Step-by-step explanation:

$4x^2-16x-26=-21$

Add 21 on both sides.

$4x^2-16x-26+21=-21+21$

$4x^2-16x-5=0$

a=4

b=-16

c=-5

$x=\frac{-b\frac{+}{}\sqrt[]{b^2-4ac} }{2a}$

$x=\frac{-(-16)\frac{+}{}\sqrt[]{(-16)^2-4(4)(-5)} }{2(4)}$

$x=\frac{16\frac{+}{}\sqrt[]{256+80} }{8}$

$x=\frac{16\frac{+}{}\sqrt[]{336} }{8}$

$x=\frac{16\frac{+}{}\sqrt[]{2^2*2^2*21} }{8}$

$x=\frac{16\frac{+}{}2*2\sqrt[]{21} }{8}$

$x=\frac{16\frac{+}{}4\sqrt[]{21} }{8}$

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$x=\frac{16}{8}+\frac{4\sqrt[]{21}}{8}$

$x=2+\frac{1}{2}\sqrt[]{21}$

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$x=\frac{16}{8}-\frac{4\sqrt[]{21}}{8}\\x=2-\frac{1}{2}\sqrt{{21}$